Download Chapters 12, 13, 14 Management of Hearing Loss

Introduction to Audiology
SPA 4030, Spring, 2014
COURSE NUMBER
SPA 4030
COURSE TITLE
Introduction to Audiology
SECTION
[U01 (17084)]
PLACEMENT
COURSE CREDITS
3
CLOCK HOURS
3
FACULTY
Cindy Ann Simon, Au.D.
305 663-9301 (private line in office)
954 270-0856 (cell phone)
954 583-1395 (home phone)
[email protected] – email,
[email protected] – phone email
Meetings may be set outside of the classroom at student’s request
Office address: 7000 SW 62nd Ave., Ph-S
South Miami, Florida 33143
Individual appointments possible between 4 – 5 pm in classroom
COURSE DESCRIPTION (NOT to exceed 200 spaces, including blanks)
This course will introduce the profession of audiology and its myriad components. It will review the
psychoacoustic properties of sound and hearing, anatomy and physiology of the auditory system. You will
learn common theories, tests, and (re)habilitation. You will learn types of hearing loss, the disorders that
go with them, and the test results associated with them.
COURSE OBJECTIVES
Upon completion of this course, the student will be able to:

Explain the scope of practice of the profession of audiology
 Identify types of hearing loss and where they are in the ear
 Understand common disorders, their symptoms, tests, and results
 Understand assistive devices, whether hearing aids, implants, or other devices
 Be aware of concomitant issues including but not limited to tinnitus, vertigo, psychosocial issues,
educational issues, and quality of life issues.
 Be aware of the laws that exist to help the client.
 Be aware of infection control.
TOPICAL OUTLINE
SYLLABUS FOR SPA 4030
May 12:
Introductions, Course Overview, Basic acoustics,
Anatomy and Physiology, Chapt 1 - 2
May 19:
Continuation of the class above
1
Assignments due on comparison of ASHA and AAA
scope of practice
May 26:
No Class, Memorial Day
June 02:
Exam on anatomy and physiology
Chapter 3 & 4, begin to look at Hepfner book
Begin types of hearing loss: conductive,
sensori-neural, mixed, pseudohypacusis
June 09:
Continue with what is left from May 23
June 16:
(1) Continue with HL and disorders
(2) Chapter 5 & 6 – types of disorders, where they
occur, and type of hearing loss caused
Begin the Alphabet Soup of terminology
June 23:
Chapter 6
The Alphabet Soup of Terminology: SPL, HL, SL,
SRT, MCL, UCL, SDT, masking, crossover, types of
masking, tuning fork tests continued
June 30:
(1) symbols of the audiogram, how to plot the
audiogram, how to do the test, speech audiometry
In Hepfner book, begin cases 1 - 15
July 07:
Chapter 8 & 9
Immittance/Impedance testing.
Otoacoustic emissions testing, ABR
July 14:
(1) Look at the big picture of the audiogram,
speech results, immitance results, OAEs, and other
special tests and what they mean together.
(2) Begin to tie in disorders of the various parts of
the ear and their auditory tests results.
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(3) Cases 1 through 15 from Hepfner book due
(4) Review cases assignment with class
July 21:
July 28:
(1) Exam 2
(2) Begin chapters 10, 12, 13
Continue with Chapters 10, 12, 13
(1) Variations of test procedures for children and
their management (Rehab) of their hearing
loss.
(2) Some infection control. Tie up loose ends.
(1)
Hearing aids, their parts, what they do, types
of circuitry.
(2) Aural (re)Habilitation and Counseling in Adults
August 4:
Final exam
Please note that the readings are approximate.
The class is fluid and things may be taken out of order,
depending on the needs of the class.
We may meet on Sundays as desired to review audios.
Please note that the readings are approximate.
The class is fluid and things may be taken out of order, depending on the
needs of the class.
Additionally, we may meet on Sundays as desired to review audios.
TEACHING STRATEGIES
The class is mostly lecture by the instructor. There will be some presentations by students.
There may be guest speakers as well. Additional time to practice audiogram will be offered
outside of class with the instructor. Class will receive all notes and audiograms examples for the
course in advance of the beginning of the course.
EVALUATION METHODS
There will be 3 examinations and 2 assignments. All points will be totaled together and divided by 3 to
obtain your grade. Please see the University’s grading system to determine the points needed for each
grade range.
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REQUIRED TEXTS
1. Clinical Audiology – An Introduction 2nd edition by Brad Stach
2. The Audiogram Workbook by Sharon T. Hepfner.
SUPPLEMENTAL TEXTS OR MATERIALS
Materials will be sent to students prior to the first day of class.
UNIVERSITY DROP DATE FOR THE COURSE – see your University schedule
FIU POLICIES
Attendance Policy
(As per the department)
Instruction Policy regarding Make-up for Exams, Assignments, or Performance Measures
This instructor needs to be notified in advance of any issues with examinations or assignments and
arrangements made prior to the schedules date.
Students with Disabilities
If you have a disability and need assistance, please contact the Disability Resource Center (University Park:
GC190; 305-348-3532) (North Campus: WUC139, 305-919-5345). Upon contact, the Disability Resource
Center will review your request and contact your professors or other personnel to make arrangements for
appropriate modification and/or assistance.
Sexual Harassment
For information on sexual harassment, please visit:
http://regulations.fiu.edu/regulation
Religious Holy Days
The University's policy on religious holy days as stated in the University Catalog and Student Handbook
will be followed in this class. Any student may request to be excused from class to observe a religious holy
day of his or her faith.
Academic Integrity
To view our Code of Academic Integrity, please visit:
http://academic.fiu.edu/AcademicBudget/misconductweb/Code_of_Academic_Integrity.pdf
Academic Misconduct
Florida International University is a community dedicated to generating and imparting knowledge
through excellent teaching and research, the rigorous and respectful exchange of ideas, and
community service. All students should respect the right of others to have an equitable
opportunity to learn and honestly to demonstrate the quality of their learning. Therefore, all
students are expected to adhere to a standard of academic conduct, which demonstrates respect
for themselves, their fellow students, and the educational mission of Florida International
University. All students are deemed by the University to understand that if they are found
responsible for academic misconduct, they will be subject to the Academic Misconduct
procedures and sanctions, as outlined in the Student Handbook. Students who plagiarize or cheat
can be charged with academic misconduct. Penalties for academic misconduct can include up to
dismissal from the University.
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Misconduct includes:
Cheating: The unauthorized use of books, notes, aids, electronic sources; or assistance from
another person with respect to examinations, course assignments, field service reports, class
recitations; or the unauthorized possession of examination papers or course materials, whether
originally authorized or not.
Plagiarism: The use and appropriation of another's work without any indication of the source and
the representation of such work as the student's own. Any student, who fails to give credit for
ideas, expressions or materials taken from another source, including internet sources, is guilty of
plagiarism.
As a student taking this class:

I will not represent someone else’s work as my own.

I will not cheat, nor will I aid in another’s cheating.

I will be honest in my academic endeavors.

I understand that if I am found responsible for academic misconduct, I will be subject to the
academic misconduct procedures and sanctions as outlined in the Student Handbook.

I promise to adhere to FIU’s Student Code of Academic Integrity.
Failure to adhere to the guidelines stated above may result in one of the following:

Expulsion: Permanent separation of the student from the University, preventing readmission to
the institution. This sanction shall be recorded on the student's transcript.

Suspension: Temporary separation of the student from the University for a specific period of
time.
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What is audiology and what is an audiologist? (the AAA
website with some additions from your instructor:)
What is Audiology and what is an Audiologist?
• Au-di-ol-o-gists: Audiologists are the primary health-care
professionals who evaluate, diagnose, treat, and manage
hearing loss and balance disorders in adults and children.
• Audiologists
a. prescribe and fit hearing aids
b. evaluate and diagnose HL and balance
c. assist in cochlear implant programs
d. perform ear- or hearing-related surgical
monitoring
e. design and implement hearing conservation
programs (incl measuring sound levels)
f. design and implement newborn hearing
screening programs
g. provide rehabilitation training such as
i. auditory training
ii. speech reading
iii. listening skills improvement (incl. APD)
iv. vestibular rehab for BPPV
v. tinnitus therapy
h. may consult or work for industry in the
design, development and training of new
technology
i. audiologists may be professors in universities
j. may deal with forensics as in expert witness
within their speciality
k. work in auditory, vestibular, tinnitus and
related research
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l. let’s not forget the basics – perform
diagnostic evaluations for auditory and
vestibular problems (must be performed
before any of the above can exist)
m. cerumen management as needed and trained
n. design and implement newborn screening
o. assess and treat debilitating tinnitus or
misophonia
p. treat all ages from newborn throughout the
lifespan
q. Audiologists may work as consultants when
designing and building classrooms, meeting
rooms in retirement homes, etc. in order to
reduce reverberation and increase a listeningfriendly environment.
• While most audiologists earn a doctor of audiology (AuD)
degree, there are other doctoral degrees that audiologists can
obtain, i.e., PhD, ScD, etc., from accredited universities with
special training in the prevention, identification, assessment,
and treatment of hearing disorders.
• Audiologists must be licensed in most states.
• Audiologists treat all ages and types of hearing loss: adults,
teens, children, and infants.
• Audiologists work in a variety of settings, such as:
 private practice & other nonresidential health-care facilities
 private practice
 private or public clinics
 ENT offices
 community and university speech and hearing center
 hospital or medical center facility, including government,
military, and VA hospitals
 school setting (K – 12)
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 residential health-care facilities including subacute
rehabilitation, long-term care and intermediate-care
facilities
 industry
 hearing aid manufacturers
 industrial hearing conservation
 other related agencies (i.e. United Way)
 university settings
 Other medical specialties
 pediatrics, including neonatology
 neurology, including neurosurgery
 oncology
 infectious diseases
 medical genetics
 community and family medicine
 gerontology
(in addition to all the above) Audiologists provide
academic education to students and practitioners in
universities, to medical and surgical students and
residents, and to other related professionals. Such
education pertains to the identification, functional
diagnosis/assessment, and non-medical
treatment/management of auditory, vestibular,
balance, and related impairments.
• Almost all types of hearing loss are treatable by an audiologist.
• Most hearing loss that is caused by nerve damage can be
treated by an audiologist with hearing aids, assistive listening
devices, and hearing rehabilitation.
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Please note that the scope of practice and definitions from AAA and ASHA can be found in the back of
your text at appendix A and B in their entirety.
The AAAScope of Practice document updated January 2004 says:
The Scope of Practice document describes the range of interests,
capabilities and professional activities of audiologists. It defines
audiologists as independent practitioners and provides examples of
settings in which they are engaged. It is not intended to exclude the
participation in activities outside of those delineated in the document.
As a dynamic and growing profession, the field of audiology will
change over time as new information is acquired. This Scope of
Practice document will receive regular review for consistency with
current knowledge and practice.
services, and the general public.
Definition of an Audiologist
An audiologist is a person who, by virtue of academic
degree, clinical training, and license to practice and/or
professional credential, is uniquely qualified to provide a
comprehensive array of professional services related to the
prevention of hearing loss and the audiologic identification,
assessment, diagnosis, and treatment of persons with
impairment of auditory and vestibular function, and to the
prevention of impairments associated with them. Audiologists
serve in a number of roles including clinician, therapist,
teacher, consultant, researcher and administrator. The
supervising audiologist maintains legal and ethical
responsibility for all assigned audiology activities provided by
audiology assistants and audiology students.
The central focus of the profession of audiology is concerned
with all auditory impairments and their relationship to
disorders of communication. Audiologists identify, assess,
diagnose, and treat individuals with impairment of either
peripheral or central auditory and/or vestibular function, and
strive to prevent such impairments.
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Audiologists provide clinical and academic training to
students in audiology. Audiologists teach physicians,
medical students, residents, and fellows about the
auditory and vestibular system. Specifically, they
provide instruction about identification, assessment,
diagnosis, prevention, and treatment of persons with
hearing and/or vestibular impairment. They provide
information and training on all aspects of hearing and
balance to other professions including psychology,
counseling, rehabilitation, and education. Audiologists
provide information on hearing and balance, hearing
loss and disability, prevention of hearing loss, and
treatment to business and industry. They develop and
oversee hearing conservation programs in industry.
Further, audiologists serve as expert witnesses within
the boundaries of forensic audiology.
The audiologist is an independent practitioner who provides
services in hospitals, clinics, schools, private practices and
other settings in which audiologic services are relevant such
as industry (measuring noise and designing protection) and
with hearing aid manufacturers for design development,
and/or training of new technology and products).
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Scope of Practice
The scope of practice of audiologists is defined by the training and
knowledge base of professionals who are licensed and/or
credentialed to practice as audiologists. Areas of practice include the
audiologic identification, assessment, diagnosis and treatment of
individuals with impairment of auditory and vestibular function,
prevention of hearing loss, and research in normal and disordered
auditory and vestibular function. The practice of audiology includes:
Identification
Audiologists develop and oversee hearing screening
programs for persons of all ages to detect individuals with
hearing loss. Audiologists may perform speech or language
screening, or other screening measures, for the purpose of
initial identification and referral of persons with other
communication disorders.
Assessment and Diagnosis
Assessment of hearing includes the administration and
interpretation of behavioral, physioacoustic, and
electrophysiologic measures of the peripheral and central
auditory systems. Assessment of the vestibular system
includes administration and interpretation of behavioral and
electrophysiologic tests of equilibrium. Assessment is
accomplished using standardized testing procedures and
appropriately calibrated instrumentation and leads to the
diagnosis of hearing and/or vestibular abnormality.
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Treatment
The audiologist is the professional who provides the full
range of audiologic treatment services for persons with
impairment of hearing and vestibular function. The
audiologist is responsible for the evaluation, fitting, and
verification of amplification devices, including assistive
listening devices. The audiologist determines the
appropriateness of amplification systems for persons with
hearing impairment, evaluates benefit, and provides
counseling and training regarding their use. Audiologists
conduct otoscopic examinations, clean ear canals and
remove cerumen, take ear canal impressions, select, fit,
evaluate, and dispense hearing aids and other amplification
systems. Audiologists assess and provide audiologic
treatment for persons with tinnitus using techniques that
include, but are not limited to, biofeedback, masking, hearing
aids, education, and counseling.
Audiologists also are involved in the treatment of persons
with vestibular disorders. They participate as full members of
balance treatment teams to recommend and carry out
treatment and rehabilitation of impairments of vestibular
function.
Audiologists provide audiologic treatment services for infants
and children with hearing impairment and their families.
These services may include clinical treatment, home
intervention, family support, and case management.
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The audiologist is the member of the implant team (e.g., cochlear
implants, middle ear implantable hearing aids, fully implantable
hearing aids, bone anchored hearing aids, and all other
amplification/signal processing devices) who determines
audiologic candidacy based on hearing and communication
information. The audiologist provides pre and post surgical
assessment, counseling, and all aspects of audiologic treatment
including auditory training, rehabilitation, implant programming,
and maintenance of implant hardware and software.
The audiologist provides audiologic treatment to persons with
hearing impairment, and is a source of information for family
members, other professionals and the general public. Counseling
regarding hearing loss, the use of amplification systems and
strategies for improving speech recognition is within the expertise
of the audiologist. Additionally, the audiologist provides
counseling regarding the effects of hearing loss on
communication and psycho-social status in personal, social, and
vocational arenas.
The audiologist administers audiologic identification, assessment,
diagnosis, & treatment programs to children of all ages with
hearing impairment from birth & preschool through school age.
The audiologist is an integral part of the team within the school
system that manages students with hearing impairments &
students with central auditory processing disorders. The
audiologist participates in the development of Individual Family
Service Plans (IFSPs) and Individualized Educational Programs
(IEPs), serves as a consultant in matters pertaining to classroom
acoustics, assistive listening systems, hearing aids,
communication, & psycho-social effects of hearing loss, and
maintains both classroom assistive systems as well as students'
personal hearing aids. The audiologist administers hearing
screening programs in schools, & trains & supervises non
audiologists performing hearing screening in the ed setting.
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Hearing Conservation
The audiologist designs, implements and coordinates industrial
and community hearing conservation programs. This includes
identification and amelioration of noise-hazardous conditions,
identification of hearing loss, recommendation and counseling on
use of hearing protection, employee education, and the training
and supervision of non audiologists performing hearing screening
in the industrial setting.
Intraoperative Neurophysiologic Monitoring
Audiologists administer and interpret electrophysiologic
measurements of neural function including, but not limited to,
sensory and motor evoked potentials, tests of nerve conduction
velocity, and electromyography. These measurements are used in
differential diagnosis, pre- and postoperative evaluation of neural
function, and neurophysiologic intraoperative monitoring of central
nervous system, spinal cord, and cranial nerve function.
Research
Audiologists design, implement, analyze and interpret the
results of research related to auditory and balance systems.
Additional Expertise
Some audiologists, by virtue of education, experience and
personal choice choose to specialize in an area of practice not
otherwise defined in this document. Nothing in this document
shall be construed to limit individual freedom of choice in this
regard provided that the activity is consistent with the American
Academy of Audiology Code of Ethics. For example, as
consultants to buildings such as schools and nursing homes
desiring acoustically friendly construction to eliminate problems
such as reverberation.
Now let’s look at what ASHA has to say:
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Definition of an Audiologist
Audiologists are professionals engaged in autonomous practice to
promote healthy hearing, communication competency, and quality
of life for persons of all ages through the prevention, identification,
assessment, and rehabilitation of hearing, auditory function,
balance, and other related systems. (also in your book on page 4)
They facilitate prevention through the fitting of hearing protective
devices, education programs for industry and the public, hearing
screening/conservation programs, and research. The audiologist
is the professional responsible for the identification of impairments
and dysfunction of the auditory, balance, and other related
systems. Their unique education and training provides them with
the skills to assess and diagnose dysfunction in hearing, auditory
function, balance, and related disorders. The delivery of
audiologic (re)habilitation services includes not only the selecting,
fitting, and dispensing of hearing aids and other hearing assistive
devices, but also the assessment and follow-up services for
persons with cochlear implants. The audiologist providing
audiologic (re)habilitation does so through a comprehensive
program of therapeutic services, devices, counseling, and other
management strategies. Functional diagnosis of vestibular
disorders and management of balance rehabilitation is another
aspect of the professional responsibilities of the audiologist.
Audiologists engage in research pertinent to all of these domains.
now to what they consider the scope of practice
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Professional Roles and Activities
Audiologists serve a diverse population and may function in one
or more of a variety of activities. The practice of audiology
includes:
1. Prevention
1. Promotion of hearing wellness, as well as the
prevention of hearing loss and protection of hearing
function by designing, implementing, and coordinating
occupational, school, and community hearing
conservation and identification programs;
2. Participation in noise measurements of the acoustic
environment to improve accessibility and to promote
hearing wellness.
2. Identification
1. Activities that identify dysfunction in hearing, balance,
and other auditory-related systems;
2. Supervision, implementation, and follow-up of newborn
and school hearing screening programs;
3. Screening for speech, orofacial myofunctional disorders,
language, cognitive communication disorders, and/or
preferred communication modalities that may affect
education, health, development or communication and
may result in recommendations for rescreening or
comprehensive speech-language pathology assessment
or in referral for other examinations or services;
4. Identification of populations and individuals with or at
risk for hearing loss and other auditory dysfunction,
balance impairments, tinnitus, and associated
communication impairments as well as of those with
normal hearing;
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5. In collaboration with speech-language pathologists,
identification of populations and individuals at risk for
developing speech-language impairments.
3. Assessment
1. The conduct and interpretation of behavioral,
electroacoustic, and/or electrophysiologic methods to
assess hearing, auditory function, balance, and related
systems;
2. Measurement and interpretation of sensory and motor
evoked potentials, electromyography, and other
electrodiagnostic tests for purposes of neurophysiologic
intraoperative monitoring and cranial nerve
assessment;
3. Evaluation and management of children and adults with
auditory-related processing disorders;
4. Performance of otoscopy for appropriate audiological
management or to provide a basis for medical referral;
5. Cerumen management to prevent obstruction of the
external ear canal and of amplification devices;
6. Preparation of a report including interpreting data,
summarizing findings, generating recommendations
and developing an audiologic treatment/management
plan;
7. Referrals to other professions, agencies, and/ or
consumer organizations.
4. Rehabilitation
1. As part of the comprehensive audiologic (re)habilitation
program, evaluates, selects, fits and dispenses hearing
assistive technology devices to include hearing aids;
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2. Assessment of candidacy of persons with hearing loss
for cochlear implants and provision of fitting, mapping,
and audiologic rehabilitation to optimize device use;
3. Development of a culturally appropriate, audiologic
rehabilitative management plan including, when
appropriate:
1. Recommendations for fitting and dispensing, and
educating the consumer and family/caregivers in
the use of and adjustment to sensory aids,
hearing assistive devices, alerting systems, and
captioning devices;
2. Availability of counseling relating to psycho social
aspects of hearing loss, and other auditory
dysfunction, and processes to enhance
communication competence;
3. Skills training and consultation concerning
environmental modifications to facilitate
development of receptive and expressive
communication;
4. Evaluation and modification of the audiologic
management plan.
4. Provision of comprehensive audiologic rehabilitation
services, including management procedures for speech
and language habilitation and/or rehabilitation for
persons with hearing loss or other auditory dysfunction,
including but not exclusive to speechreading, auditory
training, communication strategies, manual
communication and counseling for psychosocial
adjustment for persons with hearing loss or other
auditory dysfunction and their families/caregivers;
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5. Consultation and provision of vestibular and balance
rehabilitation therapy to persons with vestibular and
balance impairments;
6. Assessment and non-medical management of tinnitus
using biofeedback, behavioral management, masking,
hearing aids, education, and counseling;
7. Provision of training for professionals of related and/or
allied services when needed;
8. Participation in the development of an Individual
Education Program (IEP) for school-age children or an
Individual Family Service Plan (IFSP) for children from
birth to 36 months old;
9. Provision of in-service programs for school personnel,
and advising school districts in planning educational
programs and accessibility for students with hearing
loss and other auditory dysfunction;
10.
Measurement of noise levels and provision of
recommendations for environmental modifications in
order to reduce the noise level;
11.
Management of the selection, purchase,
installation, and evaluation of large-area amplification
systems.
5. Advocacy/ Consultation
1. Advocacy for communication needs of all individuals
that may include advocating for the rights/funding of
services for those with hearing loss, auditory, or
vestibular disorders;
2. Advocacy for issues (i.e., acoustic accessibility) that
affect the rights of individuals with normal hearing;
3. Consultation with professionals of related and/or allied
services when needed;
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4. Consultation in development of an Individual Education
Program (IEP) for school-age children or an Individual
Family Service Plan (IFSP) for children from birth to 36
months old;
5. Consultation to educators as members of
interdisciplinary teams about communication
management, educational implications of hearing loss
and other auditory dysfunction, educational
programming, classroom acoustics, and large-area
amplification systems for children with hearing loss and
other auditory dysfunction;
6. Consultation about accessibility for persons with
hearing loss and other auditory dysfunction in public
and private buildings, programs, and services;
7. Consultation to individuals, public and private agencies,
and governmental bodies, or as an expert witness
regarding legal interpretations of audiology findings,
effects of hearing loss and other auditory dysfunction,
balance system impairments, and relevant noise-related
considerations;
8. Case management and service as a liaison for the
consumer, family, and agencies in order to monitor
audiologic status and management and to make
recommendations about educational and vocational
programming;
9. Consultation to industry on the development of
products and instrumentation related to the
measurement and management of auditory or balance
function.
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6. Education/ Research/Administration
1. Education, supervision, and administration for
audiology graduate and other professional education
programs;
2. Measurement of functional outcomes, consumer
satisfaction, efficacy, effectiveness, and efficiency of
practices and programs to maintain and improve the
quality of audiologic services;
3. Design and conduct of basic and applied audiologic
research to increase the knowledge base, to develop
new methods and programs, and to determine the
efficacy, effectiveness, and efficiency of assessment
and treatment paradigms; disseminate research
findings to other professionals and to the public;
4. Participation in the development of professional and
technical standards;
5. Participation in quality improvement programs;
6. Program administration and supervision of professionals
as well as support personnel.
All the above is included in the ASHA scope of
practice.
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The following were taken from the 2nd edition of the Comprehensive Dictionary of Audiology Illustrated
AUDIOLOGY
The branch of healthcare devoted to the study, diagnosis,
treatment, and prevention of hearing disorders.
This is further broken into subspecialties:
a. educational: subspecialty devoted to the hearing
needs of school-age children in an academic setting
b. forensic: subspecialty devoted to legal proceedings
related to hearing loss and noise matters
c. pediatric: subspecialty devoted to the study,
diagnosis, and treatment of hearing impairment in
children
d. recreational: subspecialty devoted to the
conservation of hearing during recreational
activities, such as shooting, listening to music, etc.
AUDIOLOGIST
A healthcare professional who is credentialed in the
practice of audiology to provide a comprehensive array of
services related to prevention, diagnosis, and treatment of
hearing impairment and its associated communication
disorder
This was broken down into subspecialties as well
including: dispensing, educational, and pediatric
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This from ASHA, 1996
ASHA further states in the Scope of Practice that
audiologists provide their services “across the entire age
span from birth through adulthood; to individuals from
diverse language, ethnic, cultural, and socioeconomic
backgrounds; and to individuals who have multiple
disabilities.” It further notes that audiologists are
engaged in “counseling for psycho-social adjustments to
hearing loss and to persons with hearing loss, their
caregivers/families.”
From page 3 – 4 of your text – 3 definitions
Audiologist
(according to the author of this text)
A professional who, by virtue of academic degree, clinical
education, and appropriate (certification and/or) licensure
or other credential, is uniquely qualified to provide a
comprehensive array of professional services related to
the prevention of hearing loss and the audiologic
identification, diagnosis, and treatment of patients with
impairments in hearing and balance function.
According to AAA
An audiologist is a person who, by virtue of academic
degree, clinical training, and license to practice and/or
professional credential is uniquely qualified to provide a
comprehensive array of professional services related to
the prevention of hearing loss and the audiologic
identification, assessment, diagnosis, and treatment of
persons with impairment of auditory and vestibular
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function, and to the prevention of impairments associated
with them.
According to ASHA
Audiologists are professionals engaged in the autonomous
practice to promote healthy hearing, communication
competency, and quality of life for persons of all ages
through the prevention, identification, assessment, and
rehabilitation of hearing, auditory function, balance, and
other related systems.
The unique mission:
The evaluation of the auditory and vestibular system and the
amelioration of the impairments that result from auditory
(hearing) and vestibular (balance) disorders.
Audiologists may diagnose and treat and provide remediation for
disorders from any part of the auditory system from the outer ear
to the middle ear to the inner ear (including the vestibular
system) to the central auditory nervous system. Remediation or
rehabilitation may include hearing aids for hearing loss, tinnitus
maskers and counseling for tinnitus, ALDs for APD, limited
vestibular rehab such as repositioning maneuvers for vestibular
problems,
Audiologists may be found in many roles; they may be found as:
 clinicians
 therapists
 teachers, educators, supervisors
 research investigators
 administrators
 consultants – education, prevention, forensics
24
Various studies showed that 80 – 90% of hearing loss is not
medically treatable. Thus, the audiologist serves as the primary
expert in the assessment and nonmedical diagnosis of auditory
impairment.
Some situations in which SLPs and audiologists work closely
together:
a. the hearing impaired child will likely need the assistance for
speech delay
b. those children determined to have auditory perceptual
problems due to an impaired central auditory nervous
system (those with Auditory Processing Disorder or
APD)
c. with older individuals after stroke or other neurologic insult
(to determine the extent the hearing loss is impacting on
receptive language ability)
25
Chapter 2 of text
What is Sound?
Sound: a type of energy occurring as a result of pressure waves
that come from a force being applied to a sound source.
It results from the compression and rarefaction of the
molecules in the medium though which it is traveling.
As the medium is compressible or elastic, the molecules
themselves return to the point of origin, however, they
have bumped into other molecules during the
compression(aka condensation due to increased density
of molecules) and rarefaction (the elasticity allowing
reduced density of molecules) phase and those other
molecules keep the pressure waves moving and so the
energy is passed along.
So we have a (1) source of vibratory energy which (2) causes a
disturbance in a medium which (3) propagates that disturbance
as sound waves to (4) carry energy away from the source.
Vibration: to and fro movement in a mass
a. free – the mass is displaced from rest and allowed to
oscillate without outside influence
b. forced – the mass is moved back and forth by applying an
external force
There are 2 ways to define sound:
2. in a psychological sense which is the act of hearing
3. in a physical sense which is a series of disturbances of the
molecules within, and propagated through, an elastic medium
26
Waves: molecules are shoved close together and pulled apart
a. condensation – molecules are close together; increased
density of molecules during sound; a compression of
molecules
b. rarefaction – when there’s space between the areas of
compression; decreased density of molecules during sound;
an expansion of molecules.
Compression and expansion results in pressure changes that
travel though a medium such as air or water. These pressure
waves have mass, are elastic and pass energy along.
Properties of Sound
Simple harmonic motion (or sinusoidal motion): periodic back
and forth movement (and may be plotted as a function of time).
Sinusoidal waveform: a graphic display of simple harmonic
motion in magnitude versus time. Aka sine wave
Waveform: the shape of a wave seen as amplitude of
displacement versus time and this is used to describe various
properties of sound.
Magnitude of the waveform or the amplitude dictates the
intensity of the sound and is what we are more familiar with
known as loudness.
Frequency of the waveform is how often a cycle is completed and
is what we are more familiar with known as pitch.
Cycle: one complete sound wave (or an oscillation); a
condensation and rarefaction as a function of time. This
determines the frequency of a sound. Any stage of a cycle is
known as the phase. (so this is the location at any point in time
in the displacement of an air molecule during a cycle)
One cycle may also be known as the period.
Period =_____1___
Frequency
27
So if the time is for 1 second, the answer used to be cps or
cycles/second. We no longer use that term, we use the term
Hertz (Hz). So cps and Hz may be used interchangeably.
Frequency – the number of complete cycles of a vibrating body
per unit of time.
Example: If the time period you are measuring is one second
and there are 3 full cycles in that period, then the measurement
is 3 cycles/sec
Pure tone: 1 sine wave with no tones superimposed
Simple Sounds – a sound that has all its energy at one
frequency, a pure tone.
28
29
There is a large range of intensity. Barely audible sounds occur at
20 μPa and painful intensity is at 200,000,000 μPa. As these units
become rather large, intensities are described as decibels (dB).
Today, we describe intensity in decibels sound pressure level or
dBSPL. SPL is the magnitude of sound energy relative to a
reference pressure of .0002dynes/cm2 or 20μPa.
Decibels are expressed as a ratio of a measured pressure to a
reference pressure. Thus, 0 dB does not mean that there is no
sound. It just means that the measured pressure equals the
reference pressure.
Velocity – the speed with which the sound wave travels from the
source to another point. The denser the medium, the faster
sound travels as molecules are closer together and bounce off
one another faster.
Intensity: quantity or magnitude of a sound.
It is the perception of sound loudness.
The distance mass moves from the point of rest; the
amplitude a body vibrates, this is measured in dB or
decibels
Pressure: this is generated whenever force is distributed over a
surface area. Damaging sound waves have a high pressure.
So once we understand this, and we now know frequency and
intensity, another way to think of it is:
Physical Measurement
Frequency
Intensity
Psychological Correlate
Pitch
Loudness
Measurement
Hz or kHz
dB (decibels)
Decibels (dB): the units in which we measure intensity
Sound Pressure Level (SPL): the magnitude of sound energy
relative to a reference pressure. Most commonly used reference
is .0002dynes/cm2 also known as 20uPa (micropascals)
30
Remember: intensity changes are not a 1:1 relationship but a
logarithmic relationship. We change the sound pressure into
numbers we can use.
Since decibels are a ratio of a measured pressure to a reference
pressure, that does not mean that 0dB is no sound but rather the
measured pressure is equal to the reference pressure.
But when performing hearing testing we measure decibels in
hearing level.
Hearing level (HL): this is the decibels according to average
normal hearing or audiometric 0.
Normals were measured in dBSPL and at each frequency, the
average minimal level of hearing was turned into audiometric 0.
The human ear can hear from 20Hz to 20,000Hz.
We test in octaves. An octave is twice the frequency of a given
frequency. We normally test at 250Hz, 500Hz, 1000Hz, 2000Hz,
4000Hz, and 8000Hz. Not that each is double the one before. So
the next frequency tested is always an octave interval of the one
tested prior.
Waves with more than one sinusoid are complex. The content of
the complex sounds, the interaction of intensity (or magnitude)
and frequency, is known as the sound’s spectrum.
31
Terms to Know
Bel – a logarithm expressing a ratio between 2 lengthy
numbers
Decibel (dB) – 1/10 of a bel – used because the bel can be a
very long number, the unit of measurement of intensity or
loudness used in audiometrics
As these represent logarithms, we must realize it is not a 1:1
relationship. When the intensity of the wave is not doubled but
raised by three. This 3dB refers to intensity.
Sound Pressure Level (SPL) – commonly measured in
dynes/cm2, and most commonly, the reference is .0002
dynes/cm2, this is also known at 20 micropascals (Pa).
This is an absolute measurement, as we would think of
centigrade when using absolute temperatures.
When dealing with 2 sound pressure measurements to be added,
we are again dealing with logarithms and it is not a 1:1
relationship of direct addition. So, for sound pressure level, we
increase the level by 6dB when it is doubled.
Again:
When doubling intensities, we add 3dB.
When doubling sound pressure, we add 6dB.
The formula to convert to dBSPL, or sound pressure is:
( output pressure )
dBSPL = 20 X log ( referent pressure) and this is .002 dynes/cm2
The formula to convert power to decibels intensity level dBIL is:
(Wo ) Wo = watts per cm2 (power) output
dB = 10 X log ( Wr ) Wr = watts per cm2 (power) reference and
the agreed-upon intensity level is 10-16W/cm2
32
Hearing Level (HL) – this is a relative term, much as farenheit
is a relative term for temperatures.
To obtain this, a number of normal hearing adults were tested
and their hearing in SPL was converted into 0HL for each
frequency.
Example: if the average was 7dBSPL for 1Hz, then the HL level
for 7dB at 1kHz now became 0dB on the audiometer.
Sensation Level (SL) – this is another relative term, relative to
HL. It is the number of decibels above the minimum level of
hearing. Example, if someone hears speech at 30dBHL, and
you speech at 60dBHL, it is their 30dBSL at it is 30dB in
sensation level above the hearing level.
Threshold () – this is the minimum level where an individual
can hear a tone 50% of the time.
Fundamental Frequency – the lowest rate of a sound’s
vibration. This is determined by the physical properties of
the vibrating body.
Harmonics – whole-number multiples of the fundamental
frequency. So a 1000Hz tone would have a first harmonic of
2000Hz and a second harmonic of 4000Hz, etc. (aka
overtones)
Sounds can be measured by their waveforms, consisting of peaks
and valleys and the peaks are called formants. These formants
are important for vowel perception.
Moving sound encounters resistance that impedes its progress.
The more dense the medium, the more impedance there is. For
example, when the ossicles move correctly, there is little impedance.
When the stapes becomes stiff there is more mass and thus more
impedance to movement and transmission of sound.
33
Audiometric zero: the sound pressure level at which the
threshold of audibility occurs for normal listeners.
Aka audiometric zero
Frequency
250Hz
500Hz
1000Hz (1kHz)
2000Hz (2kHz)
3000Hz (3kHz)
4000Hz (4kHz)
6000Hz (6kHz)
8000Hz (8kHz)
dBSPL (absolute) dBHL (relative)
26.5
0
13.3
0
7.5
0
11.0
0
9.5
0
10.5
0
13.5
0
13.0
0
34
THE EAR
The ear can be divided into three portions:
1. The outer ear
2. The middle ear
3. The inner ear
Sound is primarily mechanical transmission till the inner ear.
Physical processing of acoustic information occurs in the outer,
middle, and inner ears.
Physiological processing begins in the inner ear and goes along
the 8th cranial nerve to the central auditory nervous system
(CANS).
Psychological processing begins in the brainstem and continues to
the auditory cortex and onward.
A problem in the first 2 portions of the ear is easily taken care of
via
a. medical treatment
b. surgery
c. hearing aids
A problem in the inner ear and beyond causes significant
difficulties that are not easily managed and requires additional
counseling and usually audiologic habilitation/rehabilitation.
Let’s look at each portion of the ear.
35
The Outer Ear
The outer ear collects sound, aids in sound localization, and may
have a protective function for the middle ear.
1. THE AURICLE, more commonly known as THE PINNA
a. the most noticeable portion of the outer ear
b. the least important portion as far as hearing is concerned
c. made of skin-covered cartilage
d. collects sound and funnels sound to the EAM
e. important for localization up and down
Some major landmarks to be familiar with are:
a. helix – the outer upper rim
b. antitragus – just above the lobule
c. lobule – earlobe or lower flabby portion
d. tragus – a small triangular protrusion which points slightly
backwards
e. concha – bowl-like shape in the middle; may increase sound
by as much as 10 – 15dB at around 4500Hz; funnels sound
into
f. External Auditory Canal or external auditory meatus (EAC or
EAM) aka the ear canal and serves as a resonator to
enhance sound at 2700Hz
36
2. THE EXTERNAL AUDITORY CANAL
a. a tunnel beginning at the concha ; 23 – 29 mm in length
b. it is elliptical, slants down at TM, and lined with skin
c. the outer 2/3 is skin-covered cartilage (continuous with the
cartilage of the pinna)
d. the inner 1/3 is skin-covered bone (bony portion of the ear
canal) and goes through the temporal bone.
e. Osseocartilaginous junction – where the 2 portions of the
EAC meet
f. Protective function to protect TM due to narrow opening and
the cerumen protects from foreign objects and creatures.
g. there are several sets of glands in the skin of the
cartilaginous portion, including those which cause cerumen
or earwax. Note: cerumen is normal and when combined
with the little hairs in the ear canal (cilia), serves as a
protective mechanism to keep foreign objects from going in
further and to minimize bacteria and fungus from infecting
the ear canal
h. In infants and very young children, the angle of the EAC is
very different from that of the adult. It slopes downward at
a sharper angle
i. The canal serves as a tube resonator for frequencies around
2700Hz for most adults by 10 – 20dB.
37
1. THE TYMPANIC MEMBRANE (EARDRUM)
a. occurs at the termination of the EAC
b. constructed in 3 layers of skin embedded in the bony
portion of the canal
i. outer layer is skin
ii. middle layer is tough, fibrous, connective tissue
which contributes most to the ability to vibrate
iii. mucous membrane which also lines the middle ear
space
c. very thin
d. concave, curving slightly inward, and taut like a drum
e. extremely efficient vibrating surface
f. rich in blood supply
g. embedded in fibrous portion is the malleus or largest bone
of the middle ear
h. umbo – tip of the malleus is set to cause the center of the
eardrum to be pulled inward and this is the point of
greatest retraction
i. annulus – a ring of tissue that holds the ear drum in
position
38
j. vibrates when sound waves hit it and vibrates with a
magnitude proportional to the intensity of sound at a
speed proportional to its frequency
k. semitransparent
When looking into the ear with an otoscope, it is common to
observe a reflection of the otoscope’s light in the anterior and
inferior quadrant and this is referred to as the cone of light.
The ear drum can be divided into 4 quadrants:
1. anterior-superior
2. posterior-superior
3. anterior-inferior
4. posterior-inferior
Has 2 main sections:
a.
pars tensa - most of the surface of the eardrum is taut, it
is the larger, inferior portion with 4 membranous layers
and much stiffer than the pars flaccida
b.
pars flaccida – smaller and more compliant, located
superiorly and has 2 layers of tissue; mostly epidermal
and mucus membrane layers aka Shrapnell’s membrane.
The external ear, comprised of the pinna and external auditory
canal up to the eardrum, provides a resonant tube through which
sound waves pass. The TM vibrates with a magnitude
proportional to the intensity (loudness) of the sound wave at a
speed proportional to its frequency (cycles/second or pitch). As
sound waves hit the eardrum, the eardrum vibrates, and then
causes vibration of the malleus, which is attached to it.
39
THE MIDDLE EAR
The average middle ear is an almost oval, air-filled space within
the temporal bone of the skull.
This is an air cavity with suspended structures within. It begins
with the inner layers of the TM. It serves as an impedance
matching device between the sound waves hitting the TM and the
fluid waves of the cochlea. Thus, they provide a bridge between
the pressure waves coming in to the TM and the fluid traveling
waves of the cochlea; it connects the tympanic membrane to the
oval window of the cochlea via the ossicular chain.
40
a. The roof is a thin layer of bone separating the middle ear
cavity from the brain.
b. Tegmen tympani – thin layer of bone separating ME cavity
from the brain
c. Fundus tympani – thin plate of bone separating ME from
jugular bulb
d. Jugular bulb – below the floor of the middle ear
e. Membranous wall – lateral part of the middle ear and
contains the TM
f. Epitympanic recess – space within the ME and above the TM
g. Eustachian tube – connects the middle ear to the
nasopharynx (area where the nose and back of the throat
come together) This keeps the middle ear at atmospheric
pressure
h. Lined with a mucous membrane and is ciliated (cilia are tiny
hairs). These hair cells create a motion that cleanses the
middle ear by moving particles down and out through the
Eustachian tube.
41
1. THE EUSTACHIAN TUBE
a. enters the ear at a 30 degree angle and passes into the
nasopharynx; it is the passage way from the nasopharynx to
the anterior wall of the ME
b. opened by the action of 3 sets of muscles and this occurs
during
i. yawning
ii. sneezing, or
iii. swallowing.
c. With sudden pressure changes, if not equalized, the TM is
pushed in and pressure is felt. May need to swallow or
valsalva
d. Keeps the air in the middle ear at atmospheric pressure
2. THE MASTOID
The skull area just behind the ear is bone that is
honeycombed with hundreds of air cells. This is called the
pneumatic mastoid of the temporal bone. The mastoid
borders the middle ear space posteriorly. The bony
protuberance behind the pinna is called the mastoid process.
3. WINDOWS
a. Oval window – filled by the base of the stapes (the smallest
bone in the body) and beyond is the inner ear.
b. Round window – covered by a thin, tough, elastic membrane
c. Promontory – a section of the inner ear that protrudes into
the middle ear. It separates the oval and round window
(oval is above and round below)
42
4. OSSICLES
a. these are the bones of the middle ear
b. they transfer the vibration of the TM to the cochlea in the IE
c. there are 3 of them
i. malleus (hammer)
- has a long process – the manubrium, embedded in the
fibrous layer of the TM
- the head is connected to the body of the incus
ii. incus (anvil)
- crus – long process which attaches to head of stapes
- short crus – fitted to a recess in the wall of the
tympanic cavity
iii. stapes (stirrup)
- has a head, neck and 2 crura
- posterior crus is longer and thinner
- crus are connected by the footplate and this base sits
in the oval window via the annular ligament.
d. Although every area of the TM is not an effective vibrator,
the area that vibrates is significantly greater than that of the
oval window, thus, the sound pressure coming in and
reaching the TM is concentrated on the oval window. Be
aware that some of the pressure is lost in the mass of the
ossicles. However, due to the physical laws of leverage, and
the fact that the force is greater at the footplate of the
stapes that that on the malleus, the ossicular chain rocks
and acts as a pivot rather than a piston.
Thus, the increased pressure + lever action give a
significantly increased pressure at the oval window.
43
So the middle ear has impedance matching characteristics. This
is why there is no loss of sound energy due to the impedance
mismatch. The ease of energy flow in air is very different than
energy flow in a fluid filled space. So the ossicular chain plays
the role of mediator between what comes in the OE and what
affects the IE. Without it, the air pressure alone would have to
set the fluid into motion and a lot of energy could be lost. With
the middle ear, the air waves are changed into mechanical energy
and this mechanical energy in the ME helps convert the energy
from air to hydraulic. It does this in 3 ways:
A. sound is collected over a large surface area (TM) and directed
to a smaller surface area (footplate of the stapes), increasing
the sound pressure by as much as 23dB.
B. TM is curved with more movement on the curved areas and
less near the manubrium. This results in an increase in the
force transmitted through the middle ear.
C. The difference in length between ossicles, from the malleus to
the incus, creates a lever-type action that result in a small
increase in sound pressure. This lever action provides a boost
of about 2.4dB to the signal.
Without these impedance matching characteristics, there could
possibly be a loss of energy of 26 to 30dB of sound during the
transmission of sound from air to fluid in the cochlea.
44
5. There are 2 main middle ear muscles:
a. stapedius muscle: this muscle is in a canal next to the
facial canal. It is innervated by a branch of the VIIth nerve
i. stapedius tendon: attached the muscle to the stapes.
The stapedius tendon is attached to the neck of the stapes
and when the muscle is contracted, the stapes moves and
tenses the oval window. It is theorized that we understand
better than we should in noise because this reduced the low
pitch parts of noise by reducing the amplitude of vibration.
This tendon also supplies blood to the lenticular process of
the incus.
b. tensor tympani muscle: the tendon from this muscle goes
into the manubrium of the malleus and when contracted
causes the malleus to move in a way that tenses the TM.
The innervation of this nerve is from the trigeminal (Vth)
nerve.
Later, we will learn of acoustic reflexes and the reflex arc. The
stapedial muscle will play a major role in the acoustic reflexes,
both ipsilateral and contralateral.
45
THE INNER EAR
The inner ear has also been called a labyrinth. There are
2 primary portions with numerous parts.
I. THE VESTIBULAR APPARATUS – balance portion
1. vestibule: the immediate entryway after just past the
oval window; through here the various partitions of
the inner ear can be reached.
2. perilymph: the fluid which fills the vestibule
3. here is where the organs of balance or the vestibular
apparatus exists
4. this system relies on the forces of gravity and inertia
5. receives input from visual and somatosensory system
or the skeletal muscular system.
6. In the vestibule are the utricle and the saccule. Both
are membranous sacs surrounded by perilymph and
containing endolymph. The saccule is slightly smaller
than the utricle. Coming off the utricle are the 3
semicircular canals, the:
a. superior semicircular canal
b. lateral semicircular canal
c. posterior semicircular canal
These are filled with endolymph and surrounded in
the cavity by perilymph. They are arranged
perpendicular to each other to cover all dimensions in
space.
7. Ampulla (ampullae pl.): enlarged areas at the end
of each canal which goes back into the utricle. Each
contains an end organ called
8. crista: an end organ in the ampulla which is used for
the sense of balance
46
9. macula of otoliths: otoconia are calcium carbonate
crystals and contains sensory receptors called
macular making hair cells sensitive to gravity
(note: the above crista of ampullae and maula of otoliths
are in the uticle)
10. When your head moves, the fluids inside this system
moves and this stimulates the entire vestibular
mechanism.
So the 5 sensory receptors in this portion are the
utricle, saccule, and the 3 semicircular canals. This all
acts as a motion detector:
a. the utricle orients to gravity and horizontal
movement, while the saccule orients in the vertical
plain (these 2 structures are responsive to linear
acceleration)
b. the semicircular canals and the ampullae are
responsive to angular acceleration (movement like
tilting your head to one side)
11. When a problem occurs, whether by illness or
damage, the result is vertigo.
12. Nystagmus: a rapid movement of the eyes that
occurs with vertigo
47
48
II. THE AUDITORY MECHANISM
1.Cochlea: a snail-like structure, 2.5 turns in the
temporal bone composed of three canals or scala
where the outermost scala are filled with perilymph
fluid and the center scala is filled with endolymph.
a. scala vestibuli: close to vestibule, topmost
portion closest to vestibular apparatus, perilymph
filled, terminates basally at the oval window
b. scala tympani: the bottom-most portion;
terminates basally at the round window,
perilymph filled
c. scala media: the middle canal, AKA as the
cochlear duct or cochlear partition and separates
the scala vestibule from the scala tympani; filled
with endolymph
- Reissner’s membrane covers the partition and
separates it from the scala vestibuli
- Basilar membrane separates it from the scala
tympani and runs the length of the cochlea from
the base to the apex, on it is the organ of Corti
which has the sensory cells of hearing
2. Helicotrema: a small passage at the tip/apex of the
cochlea which allows perilymph to go from the s.
vestibuli to the s. tympani. As the oval window is
pushed in, perilymph from the s. vestibuli flows
through the helicotrema to the s. tympani &
pushes the round window out.
3. The endolymph in the scala media, via a duct, is
continuous with the endolymph in the semicircular
canals, saccule, and vestibule.
4. Reisner’s membrane: separates scala media from
scala vestibuli
49
5. Organ of Corti: lies along the full length of the scala
media on the basilar membrane. It contains the
sensory cells of hearing of which there are 2 types
– outer hair cells (about 13,000) and inner hair
cells (about 3,500)
6. Spiral Ligament: supports the scala media
7. Stria vascularis: produces endolymph, supplies
oxygen, & other nutrients to the cochlea
8. Modiolus: the place where the blood and nerve
supply enter the cochlea; the central bony pillar of
the cochlear through which blood vessels and nerve
fibers of the labyrinth course
9. BASILAR MEMBRANE:
a. narrow at the basal end and wider at the apical
turn (the opposite of the cochlear duct)
b. has 3 – 5 parallel rows of 12,000 – 15,000 outer
hair cells (OHC) and one row of 3,500 inner hair
cells (IHC)
c. Corti’s arch: separates inner and outer hair cells
d. Stereocilia: located on top of each HC; depending
on the direction they bend, nerve impulses are
either stimulatory or inhibitory
e. Tectorial membrane – the membrane where the
stereocilia on the OHCs are embedded; gelatinous
f. When the hair cells shear, a chemical is released at
the base of the hair cell
g. Each IHC is supplied by about 20 nerve fibers.
Each nerve fiber serves only 1 hair cell
h. With OHCs, each nerve fiber may go to several
OHCs
50
i. OHCs have cilia embedded in a gelatinous layer
covering the organ of Corti know as the tectorial
membrane
j. Spiral ganglion: all nerve fibers leave the cochlea
and extend to the modiolus where the cell bodies
group together to form the spiral ganglion; a
collection of cell bodies of the auditory nerve fibers
clustered in the modiolus
k. IHCs connect to the brain and OHCs are innate
biological amplifiers
l. OHCs are susceptible to noise, disease, head
trauma, vascular problems, etc for about 40 –
60dBHL.
m. OHCs are innervated by efferent or motor fibers
of the nervous system – they take information from
the brain back to the cochlea
n. IHCs are innervated by the afferent or sensory
fibers of the nervous system – they send
information to the brain
o. IHCs do not make direct contact with the tectorial
membrane
51
52
53
10. THE AUDITORY NEURON
a. There are 2 types of neurons:
i. afferent (sensory) neurons (30,000): carries
impulses from the cochlea to the central auditory
system
ii. efferent neurons (1800): projects to the
brainstem and contacts other hair cells
b. The neurons are specialized cells designed as a
conductor of nerve impulses and consist of:
i. cell body
ii. axon: transmits impulses along the neurons
iii. dendrites: receives impulses from other nerve
cells
The axons and dendrites are a branching system.
Electrical impulses travel along the axon to be
received by the dendrites. This is accomplished
through:
i. synapses: connections between neurons
ii. neurotransmission: the act of sending
information between neurons
iii. neurotransmitters: at the connecting junction,
these are released and cause activation or
inhibition of adjacent neurons.
54
As mentioned numerous times in connection with the various
structures, there are 2 types of fluid, endolymph and perilymph.
Endolymph is high in potassium ions and low in sodium ions and
perilymph is low in potassium ions and high in sodium ions.
55
IN the past, there have been many theories of hearing. It is no
longer fashionable to go into them but be aware only of the
TRAVELING WAVE THEORY as explained by von Bekesy: as the
stapes footplate moves in and out, the basilar membrane moves
down and up due to a disturbance of the endolymph; the wave
moving down the cochlear duct from base to apex with max
amplitude for high frequency tones at the basal end and low
frequencies at the apical end. So the input frequency determines
the distance the traveling wave moves before peak as well as the
rate of basilar membrane vibration. Therefore, you can see that
the basilar membrane is arranged tonotopically.
However, the traveling wave theory does not explain the
sensitivity and frequency selectivity of the cochlea. It may be
that the sensitivity of the IHCs is controlled by the OHC and at
maximum displacement of the traveling wave, the IHCs become
stimulated, thus releasing neurotransmitters that stimulate nerve
endings.
So let’s recap what we know to the point about the energy
transmission of sound from when it enters the ear to the brain.
When sound enters the ear it is acoustical energy.
In the middle era it is changed to mechanical energy.
In the inner ear, when the fluids begin to move, we
have hydraulic energy.
As we get higher into the auditory nerve and above,
the energy becomes electrical via the synapses.
Acoustical (outer ear)  Mechanical (middle ear) 
hydraulic (inner ear)  electrical (auditory nerve and
above)
56
57
58
AUDITORY NERVE AND CENTRAL AUDITORY PATHWAYS
Almost all structures on one side of the brain have a
corresponding partner on the other side. The auditory nervous
system is filled with nuclei that serve as a relay station for neural
information from the cochlea and VIIIth nerve to other nuclei in
the ANS and to nuclei of other sensory and motor systems. The
ones involved in the primary auditory pathway of the CANS are
- cochlear nucleus
- superior olivary complex
- lateral lemniscus
- inferior colliculus
- medial geniculate
1. THE AUDITORY NERVE: this is carried in the internal auditory
canal (IAC). The IAC runs from the base of the modiolus and
ends at the base of the brain. The canal carries the vestibular
portion of the 8th nerve (the fibers going into the utricle,
saccule, and semicircular canals). But the auditory portion
spirals through like a cable, creating the nerve trunk.
a. the fibers from the basal turn (high frequencies) form
the outer portion of the cable and
b. the apical areas (low frequencies) form the center
This nerve continues past the IAC to attach to the brainstem
at the cerebellopontine angle (CPA). This is where the
cerebellum, medulla oblongata, and pons join. At this point,
the auditory and vestibular portions of the nerve separate.
The 8th nerve codes intensity as the rate of neural discharge and
it codes frequency as the place of neural discharge
(tonotopically).
59
2. THE COCHLEAR NUCLEUS: The cochlear nucleus probably
preserves but does not enhance the information it receives.
This is tonotopic as well as the cochlea. The auditory nerve
fiber termination separates into areas, one for apical turn fibers
and one for basal turn fibers, etc.
As fibers travel up the tract, some travel straight up (ipsilateral)
and some (75%) crossover to the same structure on the opposite
side of the brain (contralateral). The crossover is also called
decussation & the bundles that crossover to the other side are
called commissures. The 1st crossover point is at the trapezoid
body.
3. RETICULAR FORMATION: this “diffusely organized area” is in
the center of the brainstem and communicates everywhere.
It plays a role in auditory alertness, reflexes, and habituation.
It is responsible for (a) cardio-respiratory reflex function and
(b) fight/flight reflex (auditory based threats invoke the
reticular formation). It may have an important role in
selective attention.
4. SUPERIOR OLIVARY COMPLEX (SOC): gets most of the fibers
from the cochlear nucleus, both ipsilateral and contralateral.
Senses direction. It also functions as a relay station on the way
to the cortex. Note that this mediates the reflex activity of the
2 middle ear muscles, the crossovers where could explain the
stapedial reflex in both ears when sound is presented to one
ear. The SOC processes time & intensity cues. It (a) measures
the time of arrival of sound at each ear & (b) measures how
loud the same sound is in both ears. This is localization & how
we lock on a target sound, separate it from the noise. A –12 to
–20 S:N ratio still allows us to hear in the presence of noise. If
there is a problem in one ear, you lose localization & the ability
to listen in noise when the target sound is softer than the noise.
60
5. LATERAL LEMNISCUS: it is a major pathway for transmission
of impulses from the ipsilateral lower brainstem. It is
considered to be the primary brainstem auditory pathway.
6. INFERIOR COLLICULUS (IC): receives afferent stimulation
from both SOCs. This is in the midbrain and sensitive to
binaural stimulation. Exhibits a great degree of tonotopicity.
7. MEDIAL GENICULATE BODY (MGB): this is located in the
thalamus. At this point the nerve fibers become auditory
radiations and go up to the auditory cortex.
8. AUDITORY CORTEX: Up here is Heschl’s gyrus which is also
tonotopic. Some discrimination goes on here. Its 2 main
functions are (a) to be involved in localization and (b) to
determine what is speech and what is not; what is language
and what is not.
The ANS blood supply comes mainly from 2 sources:
a. the basilar artery supplies the auditory brainstem and its
branches supplies the brainstem structures and other
subcortical structures
b. the auditory subcortex and cortex receive the blood supply
from the middle cerebral artery (a branch of the carotid
artery).
61
Descending Auditory Pathways or the Efferent Tract
The efferent pathway starts down the same path it followed up to
terminate in the olivocochlear bundle (OCB) in the pons. When
this bundle is activated, there may be better detection of signal in
the presence of background noise.
So the afferent system provides stimulation from one ear
to both sides of the brain and the efferent system
provides inhibition to both cochleas.
The processing of speech information occurs throughout the
central auditory system with the primary location for processing
occurring in the left temporal lobe, thus the right ear is
dominant for the processing of speech.
62
Characteristic of Outer and Inner Hair Cells
Outer Hair Cells
Inner Hair Cells
About 12,000 in each cochlea
cylindrical in shape
About 3,500 in each cochlea
rounded or flask-like in shape
Makes contact with the bottom
of the tectorial membrane
does not make contact with
the tectorial membrane
Communicates mostly through
the olivocochlear bundle and
ends at the OHC
Communicates mostly with the
the 8th nerve fibers and ends
at the lower brainstem
Mostly efferent (take information Are mostly afferent; that is
from brain back to the cochlea)
they send information to the
Messages from brain tells them
brain
to stretch or shrink
Are stimulated by soft sounds
Stimulated by sounds of 40 – 60 dBSPL
Helps IHC sense soft sounds by When they are closer to the tectorial
amplifying them, the OHC shrinks membrane, the IHC can be bent and
& pulls the tectorial membrane
can send sound to the brain
closer to the tips of the IHC
Are usually damaged before IHC
Damage results in losses in the
40 – 60 dBHL range
Losses greater than 60dB, most
likely involves OHC and IHC damage
Presbycusis and NIHL thought
to cause damage to these HC
Impact noise may cause both
OHC and IHC damage
Damage may result in difficulty
understanding speech difficulty
in noise
Damage often results in difficulty
understanding speech in quiet and
in noise due to reduction of sound from
the ear to the brain
From Survey of Audiology: Fundamentals for Audiologists and Health Professional, 2nd
Edition, by DeBonis and Donohue
Some additional characteristics
Characteristic of Outer and Inner Hair Cells
63
Outer Hair Cells
Inner Hair Cells
Has 3 rows
Has 1 row
Cilia embedded in tectorial
membrane
cilia in proximity to but not touching
tectorial membrane
motor (efferent) fibers
sensory (afferent) fibers
64
So what can go wrong?
1. there can be hearing loss
2. there can be interruption of the development and
maturation processes of the central auditory system
Almost all causes of hearing loss destroy sensory cells, but,
usually not the nerve.
The fetus is able to hear by 20 – 22 weeks gestation.
Due to neuromaturation, the auditory system is adult-like at 9 –
11 years of age. Puberty is the marker for maturation in the
brain. So we need to keep everything stimulated as early as
possible for the best development.
There are 3 dimensions of sound that allows us to communicate:
a. frequency
b. intensity
c. how they change as a function of time.
The inner ear encodes this with exquisite precision. From the
brainstem and up this is decoded. So receptive language is the
processing of these basic sound characteristics essential for the
understanding of speech.
So let’s go back to neuromaturation of the auditory system and
look at synapses and how they change over time.
a. At birth there are 50 trillion synapses
b. At 1 year there are 1000 trillion synapses (it required
external stimulation to increase from 50 to 1000)
c. At age 20, there are 500 trillion.
It is not really new neurons that develop but rather dendritic
branches. At maturity, every part of the brain is connected to all
others.
65
The auditory system is so important that within 4 days after
conception, we can identify the auditory system and the auditory
structures that support hearing occurs from about the 3rd week of
gestation through the 37th week. Some developmental landmarks
for the inner ear are:
Week 4 vestibular/cochlear development
Week 7 1st coil of the cochlea, sensory cells in utricle and saccule
Week 11 2 ½ coils of the cochlea; VIII attaches to cochlear duct
Week 12 sensory cells in the cochlea (the cochlea is connected
to the brainstem)
Week 20 the cochlea is adult size
Week 22 the cochlea is functional
Note that by week 11, 2 ½ coils of the cochlea are developed.
The full adult cochlea has 2 ¾ coils. So you can see that most of
the development occurs in the first trimester (the first 12 weeks).
FIRST TEST MATERIAL ENDS HERE
66
Types of Hearing Loss
First, let’s review the pathway of sound.
1.
The sound comes in the outer ear; collected by the
concha, funneled down the ear canal and hits the
eardrum. This is acoustic energy.
2.
The middle ear now plays its role. The eardrum
vibrates and sets the 3 middle ear bones to vibrating
which pushes against the oval window. This is
mechanical energy.
3.
The piston action of the stapes pushing against the
round window sets fluid moving in the inner ear which
moves the sensory cells (cilia or hairs) in the cochlea,
causing sound to continue to the nerve of hearing. So
the mechanical energy has been transformed to
hydraulic energy to electrical energy.
Depending on where the problem is will determine the type
of hearing loss the individual will have.
We characterize hearing impairment by type (site of the
disorder) and degree of loss (extent it affects normal
function).
67
Chapter 3
One may look at hearing loss as being:
1) hearing sensitivity loss
i) conductive hearing loss
ii) sensori-neural hearing loss
iii) mixed hearing loss
2) suprathreshold hearing disorders – may or may not include
sensitivity loss
i) APD
ii) Other central issues
3) functional hearing loss – fabrication of a hearing loss
There are 3 main types of hearing loss:
1. Conductive: When we hear through the entire ear
system, the sound is conducted by air. If there is a
problem within the outer ear or middle ear system, then
the conduction of sound is partially blocked and we
cannot hear as well, the sound is attenuated. When there
is such a problem, we call it a conductive hearing loss.
2. Sensori-neural: When there is no problem in
conducting the sound through the outer ear or middle ear,
however, there is a problem in the inner ear, then the
nerve is affected. This is called a sensori-neural hearing
loss. That is because we did not know if it was the
sensory (cochlear) or neural (retrocochlear) system
affected without further testing.
3. Mixed: When there is both a problem in the conductive
mechanism (outer and middle ear) as well as a problem in
the nerve, we have both types of hearing loss and this is
called a mixed hearing loss.
The above three are losses of hearing sensitivity.
68
4. Pseudohypacusis: This is a whole other type of hearing
loss. There really is not hearing loss, even though the
individual says there is. Other names for this are
functional hearing loss, malingering, non-organic hearing
loss. We have to tease out the truth using our diagnostic
tests.
There are also auditory nervous system disorders. These
may or may not have physical hearing loss. They result in a
reduced ability to hear suprathreshold sounds properly.
5. Auditory Nervous System Impairments: This occurs
with disease or damage to the auditory nervous system
and may or may not be accompanied by physical hearing
loss.
A. retrocochlear (due to a change in neural structure
and function such as what is caused by a spaceoccupying lesion (like an acoustic neuroma) or by
stroke. The more peripheral the lesion, the more
impact on auditory function, the more central the
lesion, the less impact on auditory function.
B. APD: When the problem is from a developmental
disorder or diffuse changes, such as auditory
processing disorder in children or central changes
from the aging process, then we have Auditory
Procession Disorder. There may be ADD, LD, and
language problems. These may exhibit as receptive
language processing disorders or may be
neuropsychological disorders (auditory attention and
auditory memory – deficits in cognitive ability). In
the elderly, this is due to neural degeneration. In
children, it is generally idiopathic.
69
TYPES OF HEARING LOSS
Conductive Hearing Loss:
1. The loss of sound produced by abnormalities of the outer
ear and/or middle ear. ( Martin text)
2. This occurs if sound waves are disrupted before reaching the
inner ear (from Hearing Aids: A Guide to Selection, Wear,
and Care)
3. Type of hearing impairment resulting from an interruption of
sound transmission through an abnormal outer and/or
middle ear (Singular’s 1999 Illustrated Dictionary of
Audiology)
4. A reduction in hearing sensitivity due to a disorder of
the outer or middle ear (text) p. 102
5. reduction in hearing sensitivity despite normal cochlear
function, due to impaired sound transmission through the
external auditory meatus, tympanic membrane, and
ossicular chain (2nd edition Comprehensive Dictionary of
Audiology Illustrated)
Sensori-Neural Hearing Loss
1. The loss of sound sensitivity produced by abnormalities of
the inner ear or nerve pathways beyond the inner ear to the
brain. (Martin text)
2. This occurs when sound energy reaching the cochlea is not
properly processed or if the nerve signals are disrupted on
the way to the brain (from Hearing Aids: A Guide to
Selection, Wear, and Care)
3. Type of hearing loss stemming from a lesion in the cochlea
and in adjacent parts of the auditory nerve (Singular’s 1999
Illustrated Dictionary of Audiology)
4. A reduction in hearing sensitivity due to a disorder of
the inner ear (text) p. 103
5. cochlear or retrocochlear loss in hearing sensitivity due to
disorders involving the cochlea and/or the auditory nerve
fibers of Cranial Nerve VIII (2nd edition Comprehensive
Dictionary of Audiology Illustrated)
70
Mixed Hearing Loss
1. The sum of the hearing losses produced by abnormalities in
both the conductive and sensori-neural mechanisms of
hearing. (Martin text)
2. Both conductive and sensori-neural hearing loss. (from
Hearing Aids: A Guide to Selection, Wear, and Care)
3. Hearing loss with both conductive (outer and/or middle ear
pathology) and sensory (cochlear or auditory nerve
pathology) components. (Singular’s 1999 Illustrated
Dictionary of Audiology)
4. A reduction in hearing sensitivity due to a
combination of a disordered outer or middle ear and
inner ear (text)p. 103
5. hearing loss with both a conductive and a sensorineural
component (2nd edition Comprehensive Dictionary of
Audiology Illustrated)
Pseudohypacusis – Nonorganic hearing loss: (aka
malingering, functional hearing loss)
1. The exaggerated elevation of auditory thresholds (Martin text)
2. Faked or exaggerated hearing loss with no known physiologic
cause (Singular’s 1999 Illustrated Dictionary of Audiology)
3. The exaggeration or feigning of hearing impairment (text)
4. Hearing sensitivity loss that is exaggerated or feigned (2nd
edition Comprehensive Dictionary of Audiology Illustrated)
Another type of nonorganic loss or pseudohypacusis might be
Hysterical Deafness, defined as a rare psychogenic disorder of
hearing caused by conversion of emotional trauma to a physical
manifestation (2nd edition Comprehensive Dictionary of Audiology
Illustrated).
71
Hearing loss may also be identified by:
1. time of onset 2. time course
congenital
acute
acquired
chronic
adventitious
sudden
gradual
temporary
permanent
progressive
fluctuating
3. # ears involved
unilateral
bilateral
Hearing loss may also be identified by configuration:
Flat, sloping, reverse curve, cookie-bite, reverse cookie-bite,
precipitous, noise-induced notch, corner audiogram, etc.
72
AUDIOMETRIC SYMBOLS
right
left
air unmasked
O
X
air masked


bone unmasked


bone masked
[
]
sound field
S
aided sound field
A
or
SF
A
Red is always the right ear.
Blue is always the left ear.
Headphones are color-coded the same way.
73
p. 266 – 268 in text
The earliest tests we had for the testing of hearing were the
tuning fork tests. This helped us to differentiate where the
hearing problem might be, if anywhere.
When held in front of the ear, we are testing the conduction
system.
When held against the mastoid bone, we are testing the sensorineural system.
Some old tests used without tuning forks by ENTs were:
 the whisper test
 the watch-tick test
So tuning fork tests are preferable to the aforementioned.
Tuning forks come in different sizes.
 The larger the tines, the lower the frequency or the more the
bass.
 The smaller the tines, the higher the frequency.
This way, if using multiple tuning forks, the physician could obtain
an idea of low frequency, mid frequency, and high frequency
hearing. But guesses about hearing could only be made for the
frequency tuning forks used. There are still physicians today who
use the above methods.
74
The following are some of the more commonly used tuning fork
tests. They were all named for German otologists.
1. The Weber Test:
a. place the fork stem midline on the forehead
b. ask where they hear the sound
c. Depending on where they hear it (lateralization), we can
make certain assumptions:
i.
midline = normal or symmetrical hearing loss
(sensori-neural or conductive)
ii.
lateralize = conductive hearing loss, unilateral
sensori-neural hearing loss; if the loss is
conductive, the tone is louder in the poorer ear, if
the loss is sensori-neural, the sound is louder in
the better ear.
2. The Bing Test
a. place the fork stem on the mastoid bone
b. as you close off the ear by pressing on the tragus, ask them
if it is louder, softer, or the same when you close the ear
c. if they say:
i.
louder – then hearing is normal or sensori-neural
hearing loss
ii.
the same – then the problem is conductive
75
3. The Rinne Test: compares length of time tone is perceived by
air conduction versus bone conduction
a. alternate holding a vibrating tuning fork against the mastoid
versus next to the entrance to the ear
b. ask them where the sound is heard longer:
c. if they say:
i.
same amount of time for both – hearing is normal or
there is a sensori-neural hearing loss (positive Rinne)
ii.
heard longer on the mastoid – there is a conductive
hearing loss (negative Rinne)
4. The Schwabach Test:
a. compares examiner’s hearing and patient’s hearing
b. place the fork stem on the mastoid and alternate between
examiner and patient
c. when the patient no longer hears the tone, the examiner
places it on his/her mastoid
d. If:
i.
both stop hearing at the same time, the hearing is
normal
ii.
patient stops hearing before the examiner, then it is a
diminished Schwabach and there is a sensori-neural
hearing loss
iii. if they not only hear as long as the examiner but
beyond the examiner (prolonged Schwabach), there is
probably a conductive hearing loss.
76
Problems With Tuning Fork Tests
Problems with the Schwabach:
1. examiner must have normal hearing
2. sometimes it is difficult to distinguish between normal and
conductive loss as they hear the tone the same amount of
time
3. difficult to interpret in the case of mixed hearing loss
4. difficult to interpret in the case of asymmetrical hearing as
the better ear will hear the sound
Problems with the Rinne and Bing:
1. When the inner ear not being tested responds to the tone,
this is due to the immediate crossover of sound.
Problems with the Weber:
1. it is difficult to determine with mixed hearing loss
2. may report the tone for the wrong (better) ear because
what they hear makes no sense to them (even though they
hear it in the worse ear, they think they shouldn’t)
Note: when testing bone conduction, the entire skull vibrates.
This is a 0dB crossover. If one ear is better than another, the
better ear always responds. That is why we need the
audiometer, so we can “mask” the better ear with a noise and
separate out the test ear.
With bone conduction testing, the crossover threshold is 0dB.
With air conduction testing, the crossover threshold is about
60dB.
77
Now lets backtrack to the pseudohypacusis.
There are many reasons for this to occur.
There have been cases of hysterical hearing loss which might also
be called psychogenic hearing loss or hysterical deafness.
This might happen after a trauma, and it is possible to regain this
as it was never really lost.
Other terms for this are nonorganic hearing loss, functional
hearing loss, malingering. We must be careful using these
terms.
Various reasons for this problem:
1. hysteria
2. attention-getter (mostly children)
3. accident case for:
a. reward
b. workman’s compensation
Things to look for on your tests:
1. air conduction is greater than bone conduction
2. crossover does not occur
3. they answer you when you whisper behind their head
4. Stenger test
5. tests we will learn about being tympanometry, acoustic
reflexes, OAEs, ABRs, partial spondee response, inconsistent
speech and tone results.
78
Chapter 4 – Causes of Hearing Impairment
There are several categories of pathology and noxious influence
that adversely affect the auditory system. These include:
1. Developmental defects
a. hereditary – dominant and recessive
b. congenital or progressive
2. Infections
I. maternal
a. rubella
b. CMV
c. Herpes
d. Ingestion of teratogenic drugs (ie thalidomide or accutane)
II. acquired
a. meningitis
b. bacterial
c. Herpes
3. Toxins
a. ingestion of teratogenic drugs like thalidomide
b. exposure to toluene
c. aminoglycosides
d. chemotherapeutics
4. Trauma
a. noise trauma
b. head trauma
5. Vascular disorders
a. embolism
b. stroke
c. diabetes mellitus
6. Neural disorders
a. neuritis (inflammation of the nerve)
b. MS
7. Immune-system disorders
a. autoimmune disease
b. rheumatoid arthritis
79
8. Bone disorders
a. otosclerosis
b. otospongeosis
9. Aging
a. presbycusis
10. Tumors and other growths
a. acoustic neuroma
We can look at these disorders anatomically. Disorders of the
outer and middle ear are usually structural due to congenital
malformations or secondary to infection or trauma. They may be
hereditary or acquired.
OUTER EAR
MICROTIA
ATRESIA
MACROTIA
STENOSIS
IMPACTED CERUMEN
EXTERNAL OTITIS
PREAURICULAR TAGS
CARCINOMA OF THE AURICLE (Basal/Squamous Cell)
EXOSTOSIS/OSTEOMA
MIDDLE EAR
TYMPANIC MEMBRANE PERFORATION
OTITIS MEDIA
EUSTACHIAN TUBE DYSFUNCTION
OTOSCLEROSIS
GLOMUS TUMOR
DISARTICULATION OF OSSICULAR CHAIN
TYMPANOSCLEROSIS
CHOLESTEATOMA
BAROTRAUMA
TINNITUS (may be involved with middle ear, inner ear, or mixed losses)
80
COCHLEAR DISORDERS
1. SYNDROMIC
a. ALPORT SYNDROME
b. BOR (BRACHIO-OTO=RENAL SYNDROME)
c. CHARGE ASSOCIATION
d. PENDRED SYNDROME
e. USHER SYNDROME
f. WAARDENBURG SYNDROME
g. CERVICO-OCULO-ACOUSTIC SYNDROME
h. CHARGE ASSOCIATION
i. JERVELL AND LANGE-NIELSON SYNDROME
2. NONSYNDROMIC
a. PRESBYCUSIS
b. NOISE INDUCED HEARING LOSS/ACOUSTIC TRAUMA
c. CYTOMEGALOVIRUS (CMV)
d. RUBELLA
e. SYPHILIS
f. OTOTOXICITY
i. AMINOGLYCOSIDES
ii. ANTINEOPLASTIC DRUGS
iii. INDUSTRIAL SOLVENTS
iv. LOOP DIURETICS
g. MENINGITIS
h.LABYRINTHITIS
i. HERPES ZOSTER OTICUS
j. MENIERE’S DISEASE
k. COCHLEAR NEURITIS
l. AUTOIMMUNE DISEASE
m. BENIGN POSITIONAL PAROXYSMAL VERTIGO (BPPV)
n. PERILYMPHATIC FISTULA
o. ENLARGED VESTIBULAR AQUEDUCT SYNDROME
CENTRAL AUDITORY NERVOUS SYSTEM DISORDERS
BRAIN INFARCTS
MULTIPLE SCLEROSIS
ACOUSTIC NEUROMA (AKA COCLEOVESTIUBLAR SCHWANNOMA)
CPA TUMOR (CEREBELLOPONTINE ANGLE TUMOR)
CEREBROVASCULAR ACCIDENT (STROKE)
DIABETIC CRANIAL NEUROPATHY
AUDITORY PROCESSING DISORDERS
81
OUTER EAR
MICROTIA – congenital malformation of the auricle
This may not affect hearing in any significant way, however it may
affect sound localization and affect the acoustics of how we are
accustomed to listening to sound. Also remember, when there is a
craniofacial anomaly, there may be other abnormalities linked to it.
MACROTIA – Similar to microtia but the opposite, it is a congenital
condition of excessive enlargement of the auricle. Again, this may not
affect hearing in any significant way. They may be made smaller
surgically.
ATRESIA – another congenital malformation, primarily of the ear canal. At
some point, the ear canal is closed off. There may be no problems past
the point of closure or there may be other accompanying abnormalities
such as congenital ossicular malformations. This will cause a significant
conductive hearing loss if the sensory mechanism is intact which may
be corrected through the surgical opening of an ear canal, assuming all
structures of the middle ear are present and normal.
STENOSIS – another condition that is usually congenital, it is a narrowing
of the ear canal. Again this may or may not affect hearing. It does often
cause wax to build up in the individual. Sometimes the ear canal is
widened surgically. It may also occur later in life as the body changes.
IMPACTED CERUMEN – an accumulation of wax in the ear canal. It causes
a conductive hearing loss of varying degrees from 15dB to as much as
60dB. A good cleaning should take care of the problem.
EXTERNAL OTITIS – this is an infection of the ear canal or auricle. There
may be inflammation, bacteria, or even fungal growth. The most
common type known is “swimmer’s ear”. This can be treated by the
physician. Hearing loss, if any, is conductive and when the
inflammation is gone, hearing returns to normal.
CARCINOMA OF THE AURICLE (Basal/Squamous Cell) – There are various
types of cell carcinoma that may occur such as basal call, epidermoid,
and squamous cell. This must be treated or it can spread. Sometimes
the external portion with this problem is surgically removed. As with
the above disorders, this may or may not cause hearing loss, however,
important acoustic information dependent on the shape of the auricle
may be lost.
82
EXOSTOSIS – rounded hard bony nodule growing from the osseous
portion of the EAM and caused by extended exposure to cold water
Usually wide base, usually bilateral, history of exposure to cold, can
occlude the ear canal, not round
OSTEOMA – skin covered by bone growth, usually round, narrow base,
Usually unilateral, skin covered, may obstruct normal migration of
squamous epithelium outward
83
MIDDLE EAR
TYMPANIC MEMBRANE PERFORATION – this is a hole of the eardrum. It
may occur due to spontaneous bursting due to otitis media, a foreign
object being pushed though the canal too far, or even due to a trauma
such as extreme changes in pressure or jumping into a pool on the
side. Hearing loss may or may not occur, depending on the cause. If
there is hearing loss, it will be conductive. There may be pain and
even dizziness. Sometimes it will heal on its own. Sometimes a paper
patch is used. If this doesn’t work, an graft may be placed to replace
the damaged membrane.
OTITIS MEDIA – This is one of the most common childhood problems. It
will cause a conductive hearing loss. The most common type is OM
with effusion. Without effusion, there is just inflammation. Purulent
effusion has pus and mucoid effusion thick and mucuslike. It can be
acute or chronic or recurrent. Depending on type and duration, this
can cause educational problems. While the child has OM, there is
usually some conductive hearing loss. If left untreated, it can become
permanent and become sensori-neural. Usually, antibiotics are used
and if this does not help, then a myringotomy and placement of
ventilation tube may be needed.
EUSTACHIAN TUBE DYSFUNCTION – This tube allows for pressure
equalization between the ME and the outside. If it becomes restricted
due to swelling, or even because of the small, torturous curvature of
young children, then oxygen or fluid can be trapped. First, with
oxygen, the pressure is negative, much like being on a plane and not
equalizing. If left uncheck and to persist, then this can lead into a bout
of OM. ET dysfunction may or may not cause a conductive hearing
loss. If the negative pressure persists, then skin cells can become
trapped in a pocket and cause a cholesteatoma.
BAROTRAUMA – This occurs when there is a sudden, extreme change in
atmospheric pressure, whether due to diving and coming up too quickly
or as occurs when an airplane is descending. Even if the change is not
extreme, if the ET is not functioning correctly, this can still occur.
Extreme negative middle ear pressure may be observed. If any hearing
loss occurs, it will be conductive. If not corrected, it can become an
otitis media. Treatment may include nasal sprays and decongestants.
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GLOMUS TUMOR – This is the most common tumor of the middle ear. It
may occur on the jugular bulb, in the middle ear, or along the vagus
nerve. It is a heavy vascular supply of cells that arises in the middle
ear near the jugular bulb and may cause pulsatile tinnitus. It is bluish
in color. It may cause a conductive hearing loss and if untreated, can
press on the cochlea causing a reduction in oxygen getting to the
cochlea and thus resulting in a mixed hearing loss. Depending on the
location, there may also be facial nerve paralysis. Hearing loss maybe
anything and the most common treatment is surgery.
OTOSCLEROSIS – This is a stiffness of the ossicles in the middle ear. It
usually affects the stapes and it is usually hereditary. If a female does
not exhibit this before childbirth, it may often rear its head when she is
pregnant. It is usually hereditary and more often in women. It is
characterized by resorption of bone and then new, spongy formations
occur about the footplate of the stapes and where it attaches to the
oval window. The cure is surgical. They may chip away and free the
stapes or place a prosthesis so the ossicular chain moves and transmits
sound again. Hearing loss often begins as a low frequency conductive
hearing loss and may become a flat conductive hearing loss across all
frequencies.
DISARTICULATION OF OSSICULAR CHAIN – also known as a discontinuity.
There is a separation somewhere in the ossicular chain causing a
separation within the chain. This may occur in the incus, in the
incudostapedial joint, in the crura of the stapes, or even of the malleus.
The result would be a conductive hearing loss. Again, surgical
treatment would be necessary. Hearing aids might be selected instead.
TYMPANOSCLEROSIS – This can occur due to aging or as a change in the
structure of the tympanic membrane due to chronic otitis media. White
plaques are formed on the TM and cause an increased stiffening of the
TM. Depending on the severity, conductive hearing loss can occur.
This is usually a surgical treatment.
CHOLESTEATOMA – This can occur following chronic OM or due to a
chronic retraction pocket of the TM. A pocket of cells form and results
in a growth. If unchecked, it can erode through the bones of the skull.
Adhesions can grow on the ossicles. It may or may not cause a
conductive hearing loss, depending on the side and extent of the
growth. It must be removed surgically but should be watched as it is
not unusual for it to recur. There is also congenital cholesteatomas
which must also be removed.
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COCHLEAR DISORDERS
PRESBYCUSIS – gradually decreasing hearing due to the aging process.
Mostly affects those over age 65 with sensori-neural hearing loss.
Other issues during the normal lifetime may exacerbate this such as
noise exposure, reduced oxygen due to vascular disease, medications,
etc. Usually begins as a sloping hearing loss with most hearing loss in
the higher frequencies. Hearing aids are the only solution.
NOISE INDUCED HEARING LOSS/ACOUSTIC TRAUMA – continual exposure
to loud noises over long periods of time without ear protection will
cause a sensori-neural hearing loss. This may also occur from a onetime blast of extremely loud noise near the ear. Shorter exposures may
cause something called TTS (temporary threshold shift) such as after a
concert, when the hearing is muffled but eventually returns to normal.
When it no longer returns to normal it becomes PTS (permanent
threshold shift). Use of ear protectors to avoid loud noise and hearing
aids if desired are the only solutions.
CYTOMEGALOVIRUS (CMV) – this is a congenital infection and it induces a
sensori-neural hearing loss. This is the leading cause of congenital
hearing loss that is not genetic and it usually transmitted in utero. It
may be of delayed onset, it may be progressive, it may be
asymmetrical. The mother may not even know she has this as she may
think she only has a cold. Hearing aids or cochlear implant and
appropriate educational placement are the treatments.
RUBELLA – this is due to a viral infection and usually affects the child in
utero during the first trimester. In the 60’s, this was the leading cause
of nongenetic congenital sensori-neural hearing loss in infants and the
one of the prime factors for the development of all the educational
laws, including inclusion and mainstreaming that have occurred since.
As with CMV, hearing aids, CI, and appropriate educational placement
are the treatments.
SYPHILIS – A venereal disease which can affect hearing during the more
advanced stages if left untreated. It can be transmitted in utero from
an infected mother and may result in progressive sensori-neural
hearing loss. In adults, during the later stages of syphilis, the hearing
will deteriorate both sensory-wise and neurally. Hearing aids and
antibiotics such as penicillin if it is not too late are the treatments.
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OTOTOXICITY – sensori-neural hearing loss caused by drugs and
chemicals that are toxic to the ear. It may also affect the vestibular
system. It is usually permanent but in the case of aspirin and quinine,
it may be reversible. For the majority, hearing aids or CI will be the
only solutions. The following are the main causes of ototoxicity.
AMINOGLYCOSIDES – bacteriocidal antibiotics which include among
them amikacin, gentamicin, kanamycin,
neomycin, netilmicin, streptomycin,
tobramycin, viomycin, garamycin.
ANTINEOPLASTIC DRUGS – generally drugs for cancer – hearing
should be periodically monitored and keep the
patient well hydrated. (cisplatin/carboplatin)
INDUSTRIAL SOLVENTS – most commonly inhaled on the job are
styrene, toluene, and trichlorethylene
LOOP DIURETICS – most commonly seen with lasix, furosemide, and
ethacrynic acid. Lasix is very popular and
causes degeneration of the stria vascularis.
MENINGITIS – bacterial infection may cause inflammagion of the cochlea
or labyrinth. The meninges become inflamed. It may cause total
deafness, it may be asymmetrical. If early treatment with
corticosteroids is initiated, it may arrest the hearing loss before it
becomes severe. Hearing aids, CI, and educational placement are the
final outcomes.
LABYRINTHITIS – Also caused by infection, the vestibular labyrinth
becomes inflames and may produce vertigo, with or without hearing
loss. It may be transient or may become toxic and become permanent
along with hearing loss. In the more severe form, the membranous
labyrinth of the cochlea is usually affected and hearing loss is
permanent. Hearing aids would be suggested.
HERPES ZOSTER OTICUS – aka Ransay Hunt syndrome. Caused by the
chicken pox virus and often occurs in older people or when there is
extreme stress. Must have had the chicken pox when younger. Causes
little pimple-like eruptions that are very painful, may cause facial nerve
paralysis, dizziness, and sensori-neural hearing loss. Medical treatment
and hearing aids if necessary are the treatments.
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MENIERE’S DISEASE – often used synonymously with endolymphatic
hydrops. There is excessive fluid in the cochlea and the vestibular
labyrinth and symptoms include fullness in the ear, reduced hearing,
roaring in the ear and vertigo. Cochlear Meniere’s may only have
fluctuating hearing loss without the vertigo and vestibular Meniere’s
may have the extreme vertigo without the hearing loss. Over time, any
hearing loss may become permanent and be progressive. Often,
patients are told to watch their diet, avoid salt and caffeine, and are
given diuretics. When hearing loss is permanent, hearing aids may be
suggested.
AUDITORY NEUROPATHY/DYS-SYNCHRONY – this is a condition in which
the patient displays auditory characteristics that support normal outer
hair cell function and abnormal or sys-synchronous responses from the
8th nerve and brainstem. So the site of dysfunction is between the OHC
and brainstem. Auditory test will be normal, the OAE will be normal,
and the ABR will be abnormal or absent. Speech recognition will be
poor in noise but in quiet it is variable, may be slightly or greatly reduced.
AUTOIMMUNE DISEASE – a disorder in which the body produced antibodies
that attacks itself, one common example being rheumatoid arthritis.
May affect the auditory system and may be characterized by bilateral,
progressive, sensori-neural hearing loss. Treatment would be hearing
aids or CI.
BENIGN POSITIONAL PAROXYSMAL VERTIGO (BPPV) – a form of dizziness
characterized by latency of onset when in a certain position, severe
vertigo for seconds, transiency, and fatigability. It is the most common
cause of dizziness in the elderly but may occur due to head trauma,
cold, whiplash, etc. Otoliths made of calcium carbonate crystals are not
reabsorbed into the body and float in the semicircular canals, causing
temporary vertigo when the head is turned toward the side with the
excess. This may be cured with a canalith repositioning maneuvers.
WAARDENBURG SYNDROME – a genetic syndrome with the following as
the most common characteristics – white forelock, multi-colored iris,
with displacement of medial canthi, hearing loss. The hearing loss may
be unilateral or bilaterally, may be symmetrical or asymmetrical, may
be of any degree. Hearing aids would be helpful.
BOR (BRACHIO-OTO-RENAL SYNDROME) – these may have brachial
clefts, fistulas, cysts, renal malformation. There may be preauricular
tags. It is also possible to have hearing loss whether conductive,
sensori-neural, or mixed. Hearing aids would be the treatment.
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CHARGE ASSOCIATION – CHARGE stands for Colomboma, Heart disease,
Atresia Choanae (nasal cavity), Retarded growth, Genital Hypoplasia,
and Ear anomalies. The ear anomalies may cause any type of hearing
loss, conductive, sensori-nerual, or mixed. Depending on the child is
how the hearing loss will be handled but usually with hearing aids.
PENDRED SYNDROME – This is a recessive genetic disorder of the
endocrine metabolism. There may be goiter and congenital hearing
loss. The loss is generally symmetrical, moderate to profound, sensorineural. Treated with hearing aids.
USHER SYNDROME – This is also a recessive genetic disorder. There is
usually hearing loss that is sensori-neural as well as retinitis pigmentosa
causing a progressive loss of vision. Again, the hearing loss may be
treated with hearing aids.
TREACHER-COLLINS SYNDROME – rare genetic disorder characterized by
craniofacial abnormalities, underdevelopment of certain bones of the
head. Many involve the ear, mostly malformation of the external ear
and middle ear structures, including atresia. 40% are autosomal
dominant inheritance but 60% are likely new mutations. Most hearing
loss will be conductive.
TINNITUS – A noise in the ears or head, usually described as crickets,
whistle, steam, sometimes a roaring, but may also be voices. May
accompany middle ear, cochlear, or even CANS disorders. If there is
hearing loss, a hearing aid often helps. Sometimes maskers, TRT, or
Neuromonics device, or other devices help retrain the brain so this
becomes a nonissue. Within this family of disorders may also be found
HYPERACUSIS and a new one – MISOPHONIA. In hyperacusis, they
are unusually sensitive to sounds at levels that would normally not be
bothersome. In misophonia, they react to certain sounds, and can almost
become violent in their dislike.
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CENTRAL AUDITORY NERVOUS SYSTEM DISORDERS
BRAIN INFARCTS – some localized area is denied its normal blood supply
because of occlusion of an artery or drainage from a vein. When blood
supply is denied to an area servicing the ear, an auditory disorder can
occur, whether sensory, neural, or both. Hearing aids if possible would
be recommended.
MULTIPLE SCLEROSIS – in this disorder, the myelin sheaths of the nerves
are disrupted causing scattered areas of demyelination of white matter
within the nervous system. If the auditory nervous system is affected,
then there an be hearing disorder of any degree with speech
perception problems. The problem is retrocochlear. Hearing aids may
or may not be helpful. Medical management through medication may
sometimes arrest and even reverse the plaques.
ACOUSTIC NEUROMA (AKA COCLEOVESTIUBLAR SCHWANNOMA) – the
most common growth affecting the auditory nerve. It is always benign
and may or may not cause hearing loss, depending on the size. They
are most often unilateral and often develop from the vestibular branch
of the VIIIth nerve. There may be tinnitus, hearing loss, unsteadiness,
difficulty understanding words, etc. They are bilateral for those
suffering from NFII. If very small they may be watched, if surgically
removed, the hearing is generally lost, or the newer treatment using
the Gamma Knife may be used and then the area is monitored for
necrosis of the tumor over time. This is one way the hearing can be
preserved if it had not been affected.
CPA TUMOR (CEREBELLOPONTINE ANGLE TUMOR) – This is a tumor
arising in the angle between the cerebellum and pons where the VIIIth
nerve enters the brainstem. If large enough and presses on the nerve,
then again hearing loss may occur, and may be sensory, neural or
both. Hearing aids could be used.
CEREBROVASCULAR ACCIDENT (STROKE) – This is caused by an
interruption of the blood supply to the brain resulting in sudden loss of
function from that portion that was damaged. Hearing may or may not
be affected but usually not. Sometimes there may be problems
understanding words.
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DIABETIC CRANIAL NEUROPATHY – Diabetes mellitus is an insufficiency of
insulin with complications that include neuropathy and degenerative
alterations of blood vessels. This may attach all systems and may re
with vestibular and auditory disorders. Generally, the auditory disorder
is retrocochlear (neural). Hearing aids may or may not help.
AUDITORY PROCESSING DISORDERS – This may exhibit in multiple
symptoms. It may be merely a mild problem understanding the
teacher in a noisy class to having problems even listening at home. It
may be accompanied by distractibility and behavioral issues. There
may be problems following directions and there may be reading and
spelling problems. The elderly also tend to experience this problem
manifesting as they individual having greater difficulty understanding
words than would be indicated from the audiogram (phonemic
regression). While there may be some benefit with hearing aid use,
other programs and therapy that train to listen in noise or react more
quickly may be helpful.
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Name of Disorder
What is it?
Symptoms
Microtia/Mactritia
Microtia - congenital deformity, can be
unilateral or bilateral from birth. Ear can
be normally shaped incomplete or
absent, small…
Macrotia - LARGE EARS
Microtia, conductive hear
loss in the affected ear
Artesia/Stenosis
happens at birth, presence of bone
formation obstructs sound from
reaching the inner ear.
common to have malform
pinna but not necessary
External Otitis
inflammation or bacterial infection of the
external auditory canal and/or outer ear
(auricle) swimmers ear or ear ache
ear ache
Carcinoma of the auricle
Most common cancer involving the
outer ear
Raised, ulcerated lesion
the helix
Exostosis
Surfer Ears; development of benign
bony growths caused by the repeated
exposure to cold water and wind.
narrows the pathway trap
water and debris, and ea
in the canal, causing an
infection.
Tympanic Membrane Perforation
most common is ear infection, one bad
ear infection or many mild ones can
cause eardrum perforation
conductive hearing loss,
degree vares
Eustachian Tube Dysfunction
inflammation of the middle ear; the
space behind the ear drum. Common
ear infection in childhood.
ambien air pressure different than that
of middle ear
Otosclerosis
abnormal bone in the ossicles of the
middle ear, which leads to the fixation
of the stapes. No root cause known yet,
but have found that hereditary can play
factor
hearing loss
Glomus Tumor
benign tumors which arise from glomus
jugular. Most common tumor in the
middle ear
patient tested -looks like
ball behind the TM
Otitis Media
Cholesteatoma
Leverage of ossicles increases the
intensity of the sound to TM 25db,
therefore disarticulation results in
impairment of the passage of sound
vibrations in the inner ear.
expanding, tumorlike mass of
epithelium and cholesterol, usually
occing in the middle ear and mastoid
region
Barotrauma
condition where pressure difference b/w
the inside and outside of the eardrum
may cause discomfort
Disarticulation of the ossicular chain
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puss, inflammation middl
fullness and pain in the e
this normally comes from
head trauma, violent hea
injury
can eat into ossicles and
the bony labarynth. Type
loss is conductive
mild to severe hearing los
Persbycusis
Noise induced hearing loss/acoustic
trauma
gradual loss of hearing that occurs as
people age
trauma that occurs when exposed to
loud noises including music
typically bilateral, and
characterized by difficulty
hearing high frequencies
TTS-temporary comes ba
PTS-permenant
Ototoxicity
"ear poisoning" exposure to drugs that
damage the inner ear, specifically the
cochlea & sometimes the vestibulum
Temporary or permenant
disturbance of hearing,
balance, or both.
Meningitis
inflamation of the meinges (membranes
that protect brain and spinal cord) may
be aquired through kissing. There are
Viral/Bacterial<-most severe.
fever, nausea, and vomit
headaches. Joint pain, st
neck, and a low tolerance
bright light.
Labyrinthititis
inflammatory process of the vestibular
labyrinth membrane located at the inner
ear, in the middlemost part of the
cochelar duct.
"rapid eye movement" ca
chronic anxiety, hearing l
may or not be affected, a
tinnitus. Vertigo and Nau
problems…
change of fluid volume within a portion
of the inner ear known as the labyrinth
think of vertigo attack, roa
of ear especially in the lo
frequencies combined wi
stuffiness in the ear that m
proceed vertigo.
Meniere's Disease
dizziness and imbalance due to the
debris which is collected within the
ear… "ear rocks"
Body's own immune system attacks the
inner ear
Benign positional paroxymal vertigo
(BBPV)
Autoimmune Disease
inflamatory disease in the central
auditory system
tear in the round or oval window which
causes a leak from the perilymphatic
spaces of the bony layrinth into the
middle ear space; can happen from
head trauma, barotraumas, bony
erosion..
Multiple Sclerosis
Perilymphatic Fistula
dizziness or vertigo,
lightheadness, imbalance
nausea
degree of loss varies
WHOLE LIST… muscle
spasm, there are speech
perception problems
vertigo, dizziness, imbala
vomiting, and nausea
Herpes Zoster Oticus
Viral infection of the inner, middle, and
external ear common complication of
shingles
burning pain close to the
Shortly thereafter, eruptio
vesicles occurs in the ear
canal and sometime on th
face, trunk. Facial paralys
Acoustic Neuroma
a noncancerous tumor of the cranial 8th
nerve
most common brain tumo
located at the base of the
brain
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Rubella
"German Measles" viral infection
charac. By fever and a skin rash
resembling measles
Auditory Processing Disorders
difficulty in processing; child hears well
but can't understand speech
red bumps, fever, etc.
cause is unknown, but so
cases prove hereditary, n
technical prefiferal hearin
loss at all, you add noise
though and the discrim g
down
Usher Syndrome
inherited condition that causes serious
hearing loss present from birth and
thereafter and progressive vision loss
hearing loss is sensori ne
and ranges from modera
profound some folks have
balance problems
Waardenburg Syndrome
Genetic disorder. Very common to have
a hearing disorder with this syndrome.
Changes in both hair and
color, 2 color eyes; prem
patch of grey hair; synop
unibrow
Syphillis
STD, it is treatable
can cause tinnitus
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chapter 5
So why are we evaluating these patients?
CASE HISTORY!!!!
Get Information from referral source, patient, or family – begins
to give you an idea of where you are going.
Is it self-referral? Medical referral? Family decision? Child?
Adult? Obtain before testing patient.
This will give us an idea of what we are looking for. Maybe they
are merely looking for an augmentative device, perhaps they are
dizzy or have tinnitus. Perhaps a parent suspects a hearing loss
in a child or the child failed a screening before entering school or
at birth. Perhaps it is a workman’s comp or other litigious case.
Perhaps they have a learning disability or may have a tumor. We
begin to decide what we are going to do and the order in which
we go about it based on the information we obtain.
So a case history is a must. It can give us much valuable
information. From this, we can being to determine the onset of
the problem, possible causes (ototoxicity, NIHL, sudden onset,
hereditary disorders like otosclerosis, etc) and begin to determine
the next step in the process. It may be that we are the ones who
determine that the disorder is treatable and an ENT consultation
is needed. Or it may be that we are the ones determining that it
is the services of the SLP that is truly what is needed. Sometimes
we may be the ones to tract a dizzy or tinnitus complaint to
medications being taken/recently changed/recently added and
this may be the true cause of the problem.
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In order to truly understand the effects of hearing loss on any
individual, we must look at:
a. degree of hearing loss (mild, moderate, severe, etc.)
b. configuration of hearing loss (flat, sloping, reverse
slope, cookie-bite, precipitously sloping, low frequency,
high frequency, etc.)
c. type of hearing loss (sensori-neural, conductive, mixed,
APD)
d. speech perception deficit (if any)
e. age at onset (congenital or acquired – pre or
postlinguistic)
f. sudden or gradual (has or does not have compensatory
strategies)
g. patient’s normal communication demands (sitting home
versus being in school and learning language)
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A case history or interview, as suggested by DeBonis and
Donohue, suggest including the following questions:
1. What is the reason for your visit here today? (identify
communication difficulties, rule out medical pathology, monitor
medication effects, etc)
2. Do you believe that you have a hearing loss? (if yes,
discuss time of onset).
3. Do you believe that one ear is better than the other?
(normally, hearing is the same, asymmetry is a warning)
4. Do you believe that your hearing loss is gradual, or
have you noted any sudden changes in it? (gradual is the
norm, sudden is a warning)
5. How would you describe your ability to understand
conversational speech when on the phone? Watching
TV? In noisy environments? At distances? (Ideas for
client-specific rehab)
6. Do you experience a sensation of ringing, buzzing, or
other noises in your head or ears? If so, do these
sounds keep you awake at night? (determine disturbance
of tinnitus, a common sign of hearing loss or medical
conditions)
7. Do you experience any pain or drainage from your
ears? Do you have a plugged or fullness sensation in
one or both of your ears? Have you ever been seen by
and ENT physician? (check for ME pathology with drainage,
ME or IE pathology with stuffiness)
8. Have you experienced dizziness or a sensation that the
room is spinning (vertigo)? (Associated with numerous
problems)
9. Do you have a history of or are you currently exposed
to loud sounds, whether through your work or at home
or through hobbies/leisure activities? (to determine
likelihood of NIHL)
10. Do you currently wear hearing aids and are the aids
helping you to your satisfaction? (May need adjustment)
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11. Is there a family history of hearing loss? (genetic
etiology?)
12. What do you think may have caused your hearing
loss? (a client-centered question)
I like to add a question regarding medications they are
currently taking and medications they have taken in the
past. Many of our patients are on medications with side
effects such as tinnitus, vertigo, ototoxic hearing loss,
confustion, etc.
If your patient is a child, additional issues to look at may include:
1. If there were any difficulties during the pregnancy
2. If there were any difficulties during the birth
3. Again, familial history of hearing loss
4. Did the child reach the developmental milestones at
appropriate ages?
5. Illnesses, high fevers, ear infections, etc.
6. Are they doing well in school or any teacher comments about
difficulties observed
7. Do you have any concerns about hearing,
speech/language development, or general development?
Do we need to refer for medical consultation?
There are many common problems that are medically
treatable. Some are stenosis, impacted cerumen,
perforation, tympanosclerosis, and ossicular discontinuity.
Such reduction in function may be due to structural changes
and are amenable to medical management.
The most efficient way of answering these questions, aside from
superficial otoscopy, is through immittance audiometry – an
electroacoustic assessment technique measuring middle ear
function.
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What is the hearing sensitivity?
Measurement of hearing sensitivity – threshold
Type of hearing loss? CHL, SNHL, mixed, retrocochlear
AEP or ABR for those not measurable by conventional
methods. May make guesses from acoustic reflexes as well.
How well does the patient understand speech?
This allows for a realistic prognosis for the expectations with
amplification.
How well does the patient process the auditory information?
This evaluates auditory processing. This is the process by
which the central auditory nervous system transfers
information from the 8th nerve to the auditory cortex. This
plays a role in localization of sound and in detection of
desired signal in the presence of extraneous noise.
Does the hearing impairment cause a hearing handicap?
This is a current favorite to evaluate. It is difficult to
evaluate objectively as it is such a subjective matter. But to
evaluate this, we need to understand the difference between
hearing impairment, hearing disability, and hearing
handicap.
Hearing Impairment: refers to abnormal or reduced
function; the actual dysfunction described by the measures
of hearing status.
Hearing Disability: refers to a functional limitation imposed
by a hearing impairment
Hearing Handicap: refers to the obstacles to psychosocial
function resulting from or imposed by a disability
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Much evaluation is done via patient questionnaires. These
scales assess the extent of hearing disability as well as the
social and emotional consequences of hearing impairment.
These questionnaires are now known by the term
clinometrics. These self-assessment scales are likely the
most efficacious way of measuring the activity limitations,
the extent to which the auditory disorder is causing ah
erring problems, the extent to which the hearing problems is
affecting the quality of life. Scales have also been similarly
developed for vertigo and tinnitus. In some cases, the
effects of vertigo and tinnitus on quality of life may be worse
than the hearing loss.
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Histories
Depend on this a lot. Always listen to your patients or the
parents. Listen to how they answer the questions.
-
Statement of the problem
Why services are sought
Patient’s own attitude
Duration and degree of loss
Family history
Other pertinent history like noise exposure or trauma
Referrals
Do so when you feel additional help is needed. Forward reports
and results of audiogram. Suggested organization of a report is:
A. First paragraph: identification of the patient – name, age,
sex, history, reason for referral.
B. Second paragraph: statement of type and degree of loss,
what needs special attention, interpretation, implications for
communication difficulties.
C. Third paragraph: specific recommendations like aids,
speech, follow-up, use of ear protectors, use of tinnitus
maskers, etc.
Referral we might make:
 Physicians (usually otorhinolaryngologists) (when referring to
the doctor, state the area of concern and reason for referral.)
 Clinical psychologist (State concern and reason for referral)
 Speech-language pathologists
 Teachers of the hearing impaired
 Regular school classroom teachers
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So once referrals have been determined we need to decide:
Best fit of hearing aid for the individual (as determined by hearing
loss, life style, physical limitations if any, etc.)
Best formula for fit
Needs as determined by questionnaires
We need to give adequate orientation to the hearing aid and to
coping with limitations.
We need to ensure that educational recommendations are
observed.
We need to EMPOWER for INDEPENDENCE and
QUALITY OF LIFE for all concerned, the hearing impaired
and their family/significant others/caregivers.
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Chapter 6
THE AUDIOMETER
Pure tone audiometer: the instrument by which we measure
hearing. It measures frequency, intensity, and speech. It
runs from –10dBHL to 120dBHL for intensity and measures
from 125Hz – 12000Hz in frequency. Some special
audiometers, known as high frequency audiometers, may
measure up to 20000Hz. It also produces broad-band noise,
speech noise, and narrow-band noise. May also direct
signals from an external CD player or tape recorder for
speech testing or use a microphone for monitored live voice.
Oscillator/ Frequency dial – generates pure tones at discrete
frequencies and controlled by frequency dial.
Interruptor – the switch that may keep a sound on or keeps the
sound off until pressed; controls duration of sound.
Attenuator dial – changes the intensity of the signal – usually in
5dB steps, some may be even smaller
Frequency dial – changes the frequency of the signal
Selector switch – changes from air conduction to bone conduction
to speech, etc.
VU meter – monitors output of the oscillator, microphone, or
auxiliary items such as tape or CD player
Output Transducer – the device that converts one form of energy
to another such as acoustical or vibratory. These may
include earphones (insert or supraaural), loudspeakers, or
bone conduction vibrators.
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ANSI – American National Standards Institute – the governing
body that sets the standard for audiometers, hearing aid
specifications, etc. These may change. The current standard
is ANSI 1996, prior to this was ANSI, 1969. An association of
specialists, manufacturers, & consumers that determines
standards for measuring instruments, including audiometers.
They are the specs by which our equipment is calibrated.
ISO – International Standards Organization – another standard
used but not usually in the US, usually in Europe.
Threshold – The level at which the patient can just barely detect
the signal correctly 50% of the time. This is the same for
pure tones and speech; air conduction and bone conduction;
the “just-audible” concept
Air conduction – the hearing test as measured through supra-
aural or insert earphones, tests the entire auditory system.
Bone conduction – the hearing test via a bone vibrator, tests the
nerve of hearing directly – may be felt due to bone oscillator
vibration in those with severe hearing losses and usually
occurs at 250Hz & 500Hz. This is called a vibrotactile
response.
Masking – the introduction of a noise into the nontest ear as
needed, usually when there is great asymmetry.
a. typically used for air conduction when the difference
between ears is equal to or greater than 40 - 50dB
b. typically used for bone conduction when there is any
difference between ears
c. typically used for speech when there is a difference between
ears of 40 – 50dB or greater
Use 40dB with supra-aural headphones, 50dB with insert
earphones, and 0dB for bone
104
Insert Headphones – this is a newer way of testing, whereby a
receiver, covered by a foam cushion is inserted deeply into
the ear canal and reduces external noise (ambient noise) as
well as the need for masking. Often used with collapsing
ear canals.
Ways to respond to pure tone testing:
a. raising a hand or finger
b. pushing a button
c. verbally
d. dropping a block in a pail or box in the case of a child
false positive response: patient hears something when there is
nothing
false negative response: patient does not respond when they do
hear a tone – may happen in the case of malingerers
The pure tone audiogram: establishes threshold sensitivity across
the frequency range important for human communication and is
placed on a graph.
Hughson-Westlake “Ascending Method” or Hughson-Westlake
technique – the method by which we obtain threshold
Verbal instructions to a patient
Note that infants and children use modified methods we will
review later in the course.
Collapsing ear canal:
a. can happen with a narrow ear from the pressure of the
headphones
b. may give a false conductive hearing loss
c. may be overcome by the use of insert headphones or
holding the headphone off the ear
105
A review of testing technique – down 10dB and up 5dB
Pure tone average – this is an average by which to estimate
the severity of the hearing loss:
a. the more common average is 500Hz, 1000Hz, and 2000Hz
b. now we often use 500Hz, 1000Hz, 2000Hz, and 3000Hz for
a more accurate representation in the presence of high
frequency hearing loss.
c. Fletcher Average – when there is a precipitous drop at
1kHz, a Fletcher average may be more accurate, this is the
best 2 frequency average so in this case you might average
250Hz in.
Refer to symbols of the audiogram.
Occlusion effect – when the intensity of the tone during bone
conduction is increased due to the one of the ears being
covered. Usually for 1000Hz and below. Does not occur in
conductive hearing loss.
Vibrotactile response (VT) – usually seen at 250Hz and 500Hz
and the stimulus is felt as a vibration rather than hears; usually
occurs primarily for bone conduction testing.
Air-Bone Gap – the difference between the air conduction and
bone conduction
air conduction – bone conduction = air-bone gap
In the low frequencies, with bone conduction, they may
experience a vibrotactile response where they feel a vibration
rather than hear a response.
106
Interaural attenuation – the amount of reduction in intensity
that occurs as a signal crosses over the head (is transmitted by
bone conduction) from one ear to the other ear; the point at
which the better ear begins to respond:
a. about 40 - 50dB for air conduction (depending on phones)
b. at 0dB for bone conduction
c. also the loss of intensity of a sound introduced to one ear
and heard by the other.
Masking – a way to remove the nontest ear from the test
procedure when cross-hearing is suspected. The difference for
air conduction is based on the BC of the better ear to the AC of
the worse ear.
Noises used for pure tones are:
a. white noise
b. narrow band noise
For speech testing we use:
a. speech noise
b. pink noise
Rule for AC masking:
If the thresholds from the test ear exceed the bone conduction
threshold of the nontest ear by the amount of minimum interaural
attenuation, then masking MUST be used.
Rule for BC masking:
Always use masking in the non-test ear during bone conduction
testing if there is any difference at all between ears.
Overmasking – the noise presented is so loud that it crosses
back over to the other (test) ear and masks the test ear.
Central masking – a small shift in threshold with the
introduction of masking and the shift continues to increase
with increased noise.
107
Effective Masking – the level where increased masking noise
will no longer result in a shift of threshold
Masking dilemma – occurs when the difference between the BC
threshold in the test ear and the AC threshold in the nontest ear approaches the amount of interaural attenuation.
Most often seen in bilateral conductive hearing loss.
Review plateau method for masking to determine effective
masking
So what does the audiogram tell us?
1. gives the degree of hearing loss (mild, moderate, severe,
profound)
2. describes shape of loss (flat, sloping, low frequency, high
frequency, precipitous, cookie-bite, reverse slope or rising)
3. measures interaural symmetry (the difference between ears)
4. differentiates hearing loss (conductive, sensori-neural, mixed)
0 – 25dB
25 – 40dB
40 – 55dB
55 – 70dB
70 – 90dB
90dB+
normal hearing
mild hearing loss
moderate hearing loss
moderately severe hearing loss
severe hearing loss
profound hearing loss
Personally, I go by a slightly different scale. Once you say
moderately severe, then where is mildly severe or severely
severe? So I use the following:
0 – 25dB
25 – 40dB
40 – 60dB
60 – 90dB
90dB+
normal hearing
mild hearing loss
moderate hearing loss
severe hearing loss
profound hearing loss
As you see, there is not much of a difference.
108
chapter 7
Speech tests:
The goal is to quantify a patient’s ability to understand everyday
communication at suprathreshold levels.
Why?
- Gives us a threshold to crosscheck against our pure tone
average
- Measurement of threshold for speech
- Assists in differential diagnosis
- Assesses central auditory processing
- Gives estimates of communicative function, aided as well as
unaided
Speech reception or recognition threshold (SRT) – The
lowest level at which speech can be detected or recognized.
The minimum level where spondee words that they have
been familiarized with can be correctly detected 50% of the
time. AKA Speech detection threshold or speech recognition
threshold
Speech recognition or discrimination – the percentage
correct of 50 or 25 monosyllabic word lists presented at
some level above the SRT, usually 30 – 40SL (SL meaning
above the minimum hearing threshold of the spondee
threshold).
The ability to perceive and recognize speech
Lets us know the prognosis with amplification.
109
Speech detection threshold (SDT) = Speech awareness
threshold (SAT) – lowest level at which a speech signal is
audible or detected 50% of the time; this is used when the
individual cannot speak, has a profound hearing loss, or is a
child who cannot communicate, this may be used in place of
SRT if they cannot repeat spondees
The SDT requires that the client merely detect the present of speech, the
SRT requires that the client recognize the words. So the STD may often be
at a somewhat better threshold than the SRT as it often reflects the best
threshold.
There are some special speech tests, outside of the usual
monosyllabic words, to evaluate auditory processing, or the
transmission of information from the nerve to the auditory cortex
via the various levels of the brain that make up part of the central
auditory nervous system. Rather than just words in quiet, we tax
the system by assessing speech recognition in the presence of
competing speech signals, processing 2 different signals
presented simultaneously to both ears (dichotic listening), etc.
We may change the speech signal by using low-pass filtering,
time compression, high level suprathreshold testing (as in PB
rollover), speech in competition (as with SPIN), or dichotic
measures (as in SSW). We reduce the extrinsic redundancy of
speech to tax the system.
Speech testing can be performed via:
a. MLV – monitored live voice: the tester gives the words
while monitoring their voice level through a VU meter
b. Taped: a cassette or CD is hooked up to the audiometer
and the speech stimuli are delivered this way.
Ways to deliver speech stimuli:
a. through the headphones
b. via bone conductor
c. via speakers for sound field testing
110
Sound field testing (SF): when the stimuli, whether speech or
pure tone or noise, are delivered through speakers in the
room. This maybe used to check the efficacy of hearing aids
or to test children who won’t tolerate headphones. May also
be used for localization for infants and toddlers.
With children, pictures of the spondees may be used and the child
will point for the response.
Ensure you do not allow them to read your lips.
SRT – speech reception threshold: the point where they are
able to repeat 50% (2 out of 4) of the spondee words (compound
words of equal emphasis) correctly after they have been
familiarized with the words. ASHA recently recommended this be
changed to speech recognition threshold.
SDT – speech detection threshold: for a child who cannot
repeat or an individual who cannot discriminate words, the point
at which they are able to detect the speech and respond by
raising their hand or pushing a button.
The ability to repeat what is heard is considered open-set
material. If we use a picture-pointing test, that is a closed-set
approach, which limits possible choices.
Test procedure for SRT. Similar to Hughson-Westlake procedure.
Note that your SRT level will always be at a greater intensity
than the SDT. This is because it is easier to detect a sound
than to identify the sound. These results should be in good
agreement with the audiogram’s best pure-tone threshold.
111
Times when the SRT/SDT will not agree with the PTA
a. when there is a precipitous drop of hearing in the high
frequencies (e.g., hearing is normal at 500Hz and then drops
to 70 at 1000Hz, etc) – SRT better than PTA, closer to the
best 2 frequency average.
b. When there is a central auditory problem, the elderly may
have a problem in recognizing words and thus cannot get
50% correct – the SRT is poorer than PTA
c. In pseudohypacusis – anything goes here: NOTE: often, in
the case of spondees, they will give half the word correct
and not the other half.
d. SAT or SDT usually matches the single best frequency.
The same crossover problems for speech occur that occur for
pure tones.
If we test recognition at a number of increasing intensities, we
develop a PI function or performance versus intensity function.
When rollover occurs (the recognition scores are reduced), we
can assume there is a retrocochlear pathology.
MCL – most comfortable listening level or most
comfortable loudness level:
just talk to them and tell them to tell you when your voice is
comfortable or “just right”. I like to tell them to tell me when my
voice is at a level where they would like to listen to television for
2 hours.
UCL or ULL– uncomfortable listening level or
uncomfortable loudness level aka TD (threshold of
discomfort) and LDL (loudness discomfort level):
the level at which speech is uncomfortably loud. May also be
done with pure tones. A normal ear should tolerate 90 – 100dB.
If there are tolerance problems, it suggests a cochlear problem
and it sets the limits of the hearing aid output.
112
Dynamic Range – the difference between the SRT and the UCL
is the range of useful hearing.
There are many tests to measure speech discrimination.
a. Phonetically balanced words (PB): These are word lists and
tested using 50 or 25 words. There are a number of sets.
i.
CID W-22: a popular set of words
ii.
NU6 words: another popular set
iii. PBK words: similar to CID W-22 but for children
Other tests are:
b. CNC (consonant-nucleus-consonant)
c. High frequency emphasis
d. Nonsense-syllable lists – CVCV
e. Closed set response lists
i.
PIT – picture identification test
ii.
WIPI select picture that matches word
iii. NUCHIPS – similar to WIPI
iv. California consonant test for those with high
frequency hearing losses.
Newer tests are using sentences:
Some of these tests might include:
a. SSI (synthetic sentence identification)
b. SPIN (speech perception in noise test)
c. CST (connected speech test)
d. SIN (speech in noise test)
We use some of the speech tests in noise as the main complaint
of the hearing impaired is they can’t hear in noise and the quiet
testing is very artificial.
Sensitized tests for retrocochlear problems may be:
a. PB rollover
b. SPIN test (Speech Perception in Noise)
c. SSI (synthetic sentence index): SSI-C or SSI-I
d. SSW (Staggered Spondaic Words)
e. DSI (Dichotic Sentence Identification)
113
Appendix A
Alphabetical List of Spondaic Words
airplane
armchair
backbone
baseball
birthday
blackboard
cookbook
cowboy
doormat
drawbridge
duck pond
eardrum
earthquake
eyebrow
greyhound
hardware
headlight
horseshoe
hotdog
ice cream
inkwell
mousetrap
mushroom
northwest
nutmeg
oatmeal
outside
padlock
pancake
playground
railroad
stairway
sunset
toothbrush
whitewash
woodwork
114
CID W-22
LIST 1A
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
14.
15.
16.
17.
18.
19.
20.
21.
22.
23.
24.
25.
AN
YARD
CARVE
US
DAY
TOE
FELT
STOVE
HUNT
RAN
KNEES
NOT
MEW
LOW
OWL
IT
SHE
HIGH
THERE
EARN
TWINS
COULD
WHAT
BATHE
ACE
LIST 1A
26.
27.
28.
29.
30.
31.
32.
33.
34.
35.
36.
37.
38.
39.
40.
41.
42.
43.
44.
45.
46.
47.
48.
49.
50.
YOU
AS
WET
CHEW
SEE
DEAF
THEM
GIVE
TRUE
ISLE
OR
LAW
ME
NONE
JAM
POOR
HIM
SKIN
EAST
THING
DAD
UP
BELLS
WIRE
ACHE
LIST 2A
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
14.
15.
16.
17.
18.
19.
20.
21.
22.
23.
24.
25.
YORE
BIN
WAY
CHEST
THEN
EASE
SMART
GAVE
PEW
ICE
ODD
KNEE
MOVE
NOW
JAW
ONE
HIT
SEND
ELSE
TARE
DOES
TOO
CAP
WITH
AIR
LIST 3A
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
14.
15.
16.
17.
18.
19.
20.
21.
22.
23.
24.
25.
LIST 2A
26.
27.
28.
29.
30.
31.
32.
33.
34.
35.
36.
37.
38.
39.
40.
41.
42.
43.
44.
45.
46.
47.
48.
49.
50.
AND
YOUNG
CARS
TREE
DUMB
THAT
DIE
SHOW
HURT
OWN
KEY
OAK
NEW
LIVE
OFF
ILL
ROOMS
HAM
STAR
EAT
THIN
FLAT
WELL
BY
AIL
BILL
ADD
WEST
CUTE
START
EARS
TAN
NEST
SAY
IS
OUT
LIE
THREE
OIL
KING
PIE
HE
SMOOTH
FARM
THIS
DONE
USE
CAMP
WOOL
ARE
LIST 3A
26.
27.
28.
29.
30.
31.
32.
33.
34.
35.
36.
37.
38.
39.
40.
41.
42.
43.
44.
45.
46.
47.
48.
49.
50.
115
AIM
WHEN
BOOK
TIE
DO
HAND
END
SHOVE
HAVE
OWES
JAR
NO
MAY
KNIT
ON
IF
RAW
GLOVE
TEN
DULL
THOUGH
CHAIR
WE
ATE
YEAR
LIST 4A
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
14.
15.
16.
17.
18.
19.
20.
21.
22.
23.
24.
25.
ALL
WOOD
AT
WHERE
CHIN
THEY
DOLLS
SO
NUTS
OUGHT
IN
NET
MY
LEAVE
OF
HANG
SAVE
EAR
TEA
COOK
TIN
BREAD
WHY
ARM
YET
LIST 4A
26.
27.
28.
29.
30.
31.
32.
33.
34.
35.
36.
37.
38.
39.
40.
41.
42.
43.
44.
45.
46.
47.
48.
49.
50.
DARN (dawn)
ART
WILL
DUST
TOY
AID
THAN
EYES
SHOE
HIS
OUR
MEN
NEAR
FEW
JUMP
PALE
GO
STIFF
CAN
THROUGH
CLOTHES
WHO
BEE
YES
AM
116
Other Behavioral Measures
Remember that we talked about sensori-neural hearing loss being
so called because we cannot decide it is sensory (only a problem
in the cochlea) or neural (8th nerve and above through the brain,
aka as retrocochlear). The following are a series of tests that
were used extensively in the past as additional behavioral
measure to determine site of lesion. They have fallen into disuse
nowadays with all the other tests available. The ABR and OAE
will be discussed and are widely used. MRI and CT scans are
now extensively used as well.
To understand these tests, we must first understand the term
RECRUITMENT and ADAPTATION.
Adaptation: in an ear with a neural involvement, audibility of
suprathreshold sounds diminish rapidly due to excessive auditory
adaptation. The normal ear adapts at low levels and the audible
signal becomes inaudible. However, at loud suprathreshold
intensity levels, the sound remains audible. In the retrocochlear
disorder, the sound disappears rapidly.
Recruitment: an unusually rapid growth of loudness of an
impaired ear. Loudness grows more rapidly than normal at
intensity levels just above threshold in an ear with a cochlear
problem. It may also be defined as a disproportionate increase in
loudness as a function of intensity of the impaired ear. This is
symptomatic of the majority of hearing losses that are sensory.
There are other variations of recruitment:
1. partial recruitment – some recruitment is noted, however,
the growth never complete it to the level of the better ear.
2. hyperrecruitment – the impaired ear not only catcher up to
the better ear but appears to be louder in the impaired ear
than the normal ear with the same high intensity.
117
3. decruitment – the loudness grows more slowly in the
impaired ear than a normal ear. Even intense sounds may not
produce much loudness. This is often associated with
problems in the 8th nerve.
ABLB – Alternate Binaural Loudness Balance Test
An old popular test of recruitment.
This is a standard measurement of recruitment. We perform this
test at 2 frequencies, a low frequency (usually 500Hz) and a high
frequency (usually 2kHz). The bad ear is compared to the good
ear as intensity is increased until they are equal. Usually, the
intensity required for equal loudness is less for the impaired ear
than the normal ear. Slightly different tests with the same idea
are:
a. AMLB (Alternate Monaural Loudness Balance Test)
This test compares a normal frequency to a hearing
impaired frequency in the same ear
b. SBLB (Simultaneous Binaural Loudness Balance Test)
This test presents the tone simultaneously to both ears.
It was found that this was not a good test for recruitment.
When recruitment is found, it is suggestive of a cochlear disorder.
SISI – Short Increment Sensitivity Index
This was another popular test of recruitment.
This procedure tests the patient’s ability to detect the presence of
a 1dB increment superimposed on a tone that is presented at
20SL. It is a suprathreshold test so beware of crossover. Again,
this is presented at a low freq. and a high freq. The high
frequency scores are greater, suggestive of a cochlear disorder.
Example: Threshold of the poorer ear is 20dB at 500 and 40dB at
2kHz. A tone is presented at 500Hz with an intensity of 40dB and
every so often, it is increased by 1dB as a blip. They are to raise
their finger every time they hear it. We score for 20 blips. The
same is done at 2kHz with an intensity of 60dB. They will hear
the blip much more often at 2kHz than at 500Hz. A score over
50% indicative of recruitment and so a cochlear disorder.
118
TDT or Tone Decay Test
This is a test of adaptation.
This test represents a sustained tone to the ear. Even normal
ears will change threshold at soft levels to the sustained tone. As
with the other tests, this is performed with a low frequency
(500Hz) tone and a high frequency (2kHz) tone. A major change
may be indicative of a CNS disorder. This is a test of
adaptation. In adaptation, we know that a normal ear will
adapt to ongoing sound, especially at near threshold levels, and
eventually the sound is inaudible but higher intensity sounds will
remain audible. We also know that with a retrocochlear disorder,
audibility will be lost much faster, even at loud levels, due to
excessive auditory adaptation.
A. Olsen-Noffsinger tone decay test: Present the tone at 20dBSL.
As soon as they hear it the finger goes up and down when it
disappears. Record how long they hear it at 20dL and increase
level by 5dB without interrupting the tone. Continue in this
way until they hear it for a full minute or until 30dB above the
starting level has been reached.
B. Rosenberg tone decay test: Present and raise tone in the
same way as above, however, this goes on only for 1 minute
and the number of decibels raised at the end of a minute is the
decay.
C. STAT – suprathreshold adaptation test: Same as the others,
however, present the tone at a very loud level (usually 70dBSL
not to exceed 100 or 105dB) and this is only for 1 minute. If
complete adaptation occurs, it is positive for a neural problem
(central).
Generalizations:
Most decay is noted for high frequencies. Thus, usually a low
frequency and high frequency is tested.
Decay was very significant when there is 30dB or more in one
minute. Only moderate with 20 – 25dB of decay.
119
Bekesy Audiometry
This was another way to measure adaptation.
This was once a popular test and had its own type of audiometer.
It also measures auditory adaptation. It is a patient controlled
test. They press a button and let go, depending on whether or
not they hear the tone. A comparison is made between
continuous and pulsed tones. The patterns produced were
categorized into one of several types. Depending on the type
noted was the assumed site-of-lesion. The types and their
accompanying pathologies are as follows:
1. Type I: normal and conductive hearing loss. The tracings
overlap almost completely.
2. Type II: above 1kHz, the tracing for continuous tone drops
below the interrupted tone and this is indicative of cochlear
pathology.
3. Type III: the continuous trace shows a pronounced
separation for all frequencies and is associated with
problems beyond the cochlea (neural or central). This is the
most dramatic tracing. That is because the continuous tone
shows adaptation and so it is fading as would be seen with a
tone decay test.
4. Type IV: Similar to type II but the breakaway is at 500Hz
and the separation between the 2 tracings is 20+dB. This
may be cochlear or neural.
5. Type V: this is most often seen with nonorganic disorders.
The continuous tracing is better than the pulsed tracing
(they tend to run parallel).
120
Masking Level Differences – MLDs
This is another test still used. It measures lower brainstem
function. It measures binaural release from masking due to
interaural phase relationships. First, an identical, in-phase,
low frequency tone is present to both ears. Then noise is
added to each ear until the tone is masked. If the phase of
the tone to one ear is reversed, the tone should become
audible again. We look at the difference in threshold
between the in-phase and out-of-phase conditions. MLDs
should be greater than 7dB.
121
Chapter 7
Electrophysiological tests:
a. serve as an indication of peripheral sensitivity
b. serve as an indicator for site-of-lesion within the system
c. is objective and requires no subjective response from the
patient.
IMMITTANCE AUDIOMETRY
A test battery that has become as common as pure tones and
speech is acoustic immittance. This is a term that can be used
to refer to acoustic impedance or acoustic admittance.
Either terminology is correct, but acoustic impedance is the
inverse of acoustic immittance. It is now accepted that the BEST
measure of middle ear disorder is this battery of tests.
It has 4 main functions:
1. it is very sensitive to middle ear disorder
2. it can separate out cochlear from retrocochlear involvement
3. it may help estimate hearing sensitivity
4. it may help confirm your audiometric results
Thus we can differentiate between a medically treatable condition
versus a non-treatable condition.
Additionally, it may also give information regarding the integrity
of the facial nerve and Eustachian tube function. The former may
be important with Bell’s palsy and monitoring return of nerve
function.
122
Immittance , in general, it is a measure of how readily a system
can be set into vibration by a force.
Admittance is the ease with which energy will flow through the
vibrating system; the total energy flow through a system
Impedance is the reciprocal of admittance and is the extent to
which the system resists the flow of energy; the total opposition
to energy flow of resistance to the absorption of energy
So immittance is a term encompassing both the concepts of
impedance and admittance.
Compliance, on the measurements, measures the ability of the
eardrum and ossicular chain to move.
Immittance audiometry is now an all-encompassing term to
describe eardrum membrane impedance, compliance, or admittance.
It is also known as middle-ear measurements. All the measures of
ME function are indirect as they are determined by measurements
made in the plane of the eardrum membrane. It assesses how
energy flows through the outer and middle ears to the cochlea. It
indirectly assess the appropriateness of the flow of energy
throughout the system.
123
There are 3 (4) measurements made in the plane of the TM:
1. static acoustic compliance or immitance: mobility of
the TM at a given volume of pressure
2. tympanometry: the graph of how the ear drum is moving
as we vary the pressure from positive to negative; how the
immittance of the middle ear changes as air pressure is
varied in the external canal
3. acoustic reflexes: contraction of the middle ear muscle to
very loud sounds; a reflex of the stapedius muscle,
however, in animals it may be the tensor tympani muscle
4. acoustic reflex decay: the ability to hold the contraction
for 10 seconds)
Resistance, mass, and stiffness make up the impedance of the
system: Mass affects the high frequencies. Stiffness affects the
low frequencies.
Resistance – determined by the ligaments supporting the ossicles
Mass – determined by the weight of the ossicles and TM
Stiffness – load of fluid pressure from the inner ear on the stapes
By combining the mass and stiffness, we can obtain the
measurements needed for acoustic immittance.
One ear has a headphone or insert phone and the other ear has a
probe creating an airtight seal. A constant tone comes through the
probe side. (The probe tone is either 220Hz or 660Hz; the 660Hz
usually used with infants.) Pressure on that side is then varied and
the eardrum movement to different pressures recorded. ( The
pressure range is typically +200daPa to -200daPa although it may
go as far as -400daPa, depending on the peak pressure.) This is
based on how far back the probe tone comes as the pressure is
varied. Reflex-eliciting stimuli may be delivered ipsilaterally or
contralaterally, depending on what you are measuring.
124
Static Acoustic Compliance or Static
Immittance
C2 (eardrum at maximum compliance)
- C1 (eardrum stiffened with +200 pressure
C3 (total compliance of the TM)
.3 is the minimum compliance for normal ears
1.6 to 1.75 is the maximum compliance for normal ears
This refers to the isolated contribution of the middle ear to the
overall acoustic immittance of the system. It’s a measure of the
height of the peak relative to the minimum or start height. It
may be thought of as the absolute height of the tympanogram at
its peak. (Stress point versus maximum mobility) Thus, a normal
system and a negative system may both have the same peak or
static immittance.
If the system is below the norm, there is less than normal
mobility and the system is stiff or hypocompliant. Some
examples that could cause this problem are otitis media or
otosclerosis where the stapes is fixed.
If the system exceeds the norm, then there is greater than
normal mobility and the system is hypercompliant. Some
examples that could cause this problem are a separation of the
ossicles (disarticulation) or a very thin eardrum characterized by
abnormal elasticity (monomeric membrane). This may occur due
to a healed perforation.
When testing, one of the measurements obtained is the ear canal
volume is ECV. If the overall volume is greater than 5.0, or if one
ear’s volume is twice that of the other ear, then the ear probably
has a perforation or a patent ventilation tube.
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Tympanometry
Tympanogram: this is a chart that shows your curve of
compliance.
To measure this, we start at +200daPa (aka mmH2O), measure the
compliance, and gradually change the pressure until –200daPa.
This highest peak shows the point of greatest compliance. A lowfrequency probe tone of 220 or 226Hz is used to bounce off the TM
and measure the distance back to determine compliance at each
point of the tympanogram.
Types of tympanograms:
a. type A: this indicates normal middle ear function. It is
almost an inverted V. The limits of the peak to still remain
normal are +100daPa. The pressure in the outer ear and
the pressure of the middle ear are equal
b. type As: the peak of the curve is within normal limits but
the compliance is below .3. The “S” stands for stiff.
c. type AD: the peak of the curve is within normal limits but
the compliance is above the upper end of normal. The “D”
stands for discontinuous (or disarticulation).
d. type B: this is basically flat with little compliance and no
peak. It usually indicates fluid is present. If the probe is
packed with wax, this can occur as well as with cerumen
impaction of the ear canal or a perforation of the eardrum.
e. type C: in this, the compliance is normal but the pressure
peak exceeds the bounds of +100daPa. This might be seen
on someone after a flight or with Eustachian tube
dysfunction due to a cold.
Note:Also, probe tone frequency should be taken into account.
When testing newborns and young infants, it is common to use a
1kHz probe tone versus the 226Hz tone used for adults.
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Gradient (slope): the ratio of the height and width of the tymp.
Width
Height
All of this also helps us to evaluate for perforations, even pinhole
perforations that are invisible to the naked eye. We always get a
volume measurement of the ear canal. When there is a
perforation, it becomes very large as we are measuring the outer
ear and the middle ear together. Also, if one is volume is twice
that of the other, it is also suggestive of perforation.
Another way you might see middle ear measurements written is
with the measures for ECV, COMP, and MEP. These stand for the
following:
ECV: This stands for the ear canal volume and is given in ml.
Again, when one ear ECV is twice the other or more, or, if the
ECV is great than 5ml, there is a perforation or open tube.
COMP: This stands for the compliance measurement and should
be between .3ml and 1.75m. If below .3ml, the system is
hypocompliant and you can expect a conductive hearing loss.
There may be fluid, otosclerosis, a perf, or other ME problem. If
above 1.75, the system is hypercompliant and may or may not
have a conductive problem. There may be a disarticulation.
MEP: This stands for middle ear pressure. This is where the
peak of the most compliant point is. If it is between -100daPa
and +100daPa, then the pressure peak is normal. If it is more
negative than -100daPa, then you may have Eustachian tube
function problems.
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
Tympanometry: A tympanogram is a graphic representation of the
relationship of external auditory canal air pressure to impedance; the latter
is usually reported in terms of tone of its derivatives, compliance in
arbitrary units. Pressure in the external auditory canal is varied from -200
daPa* through +200daPa while monitoring impedance. Impedance is
lowest (maximal compliance) when pressure in the canal equals pressure
in the middle ear. Ears can be classified into three basic groups on the
basis of the configuration of the tympanogram.
o
Type A. The peak compliance occurs at or near atmospheric
pressure indicating normal pressure in the middle ear. There are
three subgroups.

A - normal shape reflects a normal mechanism

AD - A deep curve with a tall peak indicates an abnormally
compliant middle ear, as seen in ossicular dislocation or
erosion, or loss of elastic fibers in the tympanic membrane.

AS - A shallow curve indicates a stiff system, as in
otosclerosis.
o
Type B - No sharp peak, with little or no variation in impedance
over a wide range, usually secondary to non-compressible fluid in
the middle ear (otitis media), tympanic membrane perforation or
obstructing cerumen.
o
Type C - Peak compliance is significantly below zero, indicating
negative pressure (sub-atmospheric) in the middle ear space. This
finding is often indicative eustachian tube dysfunction.
*daPa = decaPascal = mm H20
One system of tympanogram classification.
A = normal
AS = stiffened tympano-ossicular system; AD = disarticulation
B = Middle ear effusion, tympanic membrane perforation or impacted cerumen
C = negative middle ear pressure.
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
Acoustic Reflex measures (AR): Contraction of the stapedius muscle
occurs with loud sounds, producing a measurable change in compliance.
Abnormalities of hearing may be suspected by the following results:
o
Elevated threshold - indicates cochlear sensitivity loss or VIII nerve
disorder
o
Absent reflex

Abnormal middle ear system

Severe sensitivity loss

VIII nerve lesion

Ipsilateral VII nerve lesion

Some otherwise "normal" ears
o
Threshold low in proportion to sensitivity level ("recruitment")- seen
in cochlear loss
o
Abnormal "shape" of reflex.
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Acoustic Reflex
The acoustic reflex is activated by the RAS or reflex activating
signal. The meter reads the decrease in compliance from the
ipsilateral (same) ear or contralateral (opposite) ear. Acoustic
reflexes may also assist in differentiating cochlear and
retrocochlear disorders based on the reflex pattern. We look at
crossed and uncrossed reflexes. There can be no reflex with a
conductive involvement of as little at 5 – 10dB air-bone gap.
Generally, pure tones are used to elicit these responses. The
response is a contraction of the stapedius muscle in response to
an acoustic stimulus that is usually at least 60dB greater than the
hearing threshold. If there is significant hearing loss (greater
than 60dB) or a conductive problem, there will be no reflex. The
ipsilateral (probe ear) is measured at 1kHz and 2kHz. The
contralateral (opposite ear) is measures at 500Hz, 1kHz, 2kHz,
and 4kHz. White noise may be used as well. The intensity of the
tone is raised until a reflex is obtained or until you hit the
maximum allowable level, whichever is first. For example,
ipsilateral reflexes have a limit of 105dB and contralateral reflexes
go to 110dB. Due to recent lawsuits, there is controversy
whether to go up to 110dB or stop at 105dB as is done with
ipsilateral reflexes. Above 110dB you will see a message to warn
that this level can cause damage to the ear.
The pattern for measuring the acoustic reflex is the same as with
all other measurement, down 10 and up 5.
So these thresholds may:
1. detect a loss of hearing above a specific degree
2. detect an auditory disorder; conductive, sensori-neural, or
central
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ART (Acoustic reflex threshold): the lowest level at which the
reflex is obtained twice.
Ipsilateral reflex pathway: a sound in that ear evokes a
response from the same ear.
Sound  OE  ME  cochlea (IE)  along 8th nerve and to the
brainstem. In the brainstem, it is received by CN  SOC  facial
nerve (VII) ipsilaterally, and descends to innervate the stapedius
muscle.
Contralateral reflex pathway: the sound goes in the ear
opposite the probe and the reflex is picked up by the ear with the
probe.
Sound  OE  ME  cochlea (IE)  along 8th nerve and to the
brainstem. In the brainstem, it is received by CN  SOC and
crosses over to the opposite SOC  facial nerve (VII)
contralaterally, and descends to innervate the stapedius muscle,
thus evoking a contralateral reflex.
The reflex will generally occur at about 85dBSL or at about 85dB
above the threshold of hearing, up to about 50 or 60dB hearing
loss. Till 70dB of hearing loss, the reflex may be elevated by that
amount above 50dB of loss. Above 70dB, the reflex will be
absent as the sound level presented is not loud enough above
threshold to elicit the reflex.
If the is a problem in any part of the chain (or reflex arc as it is
known), the reflex may be absent. By analyzing the reflex
response pattern, we begin to made educated analysis of possible
pathologies.
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Acoustic Reflex Decay
The tone is given at 10dBSL or 10dB above the reflex threshold
and maintained for 10 seconds. It the reflex does not decay to
half its original amplitude, it is negative. If it is positive, there is
a more central problem to worry about.
Abnormal decay may be defined as a 50% reduction of the reflex.
Your handout says within 5 seconds, however, all previous
literature uses 10 seconds. The Comprehensive Dictionary of
Audiology Illustrated (2nd Edition) defines acoustic reflex decay as
“perstimulatory reduction in the magnitude of the acoustic reflex
reduced by over 50% of the initial amplitude within 10 seconds of
stimulus onset”.
So…..
Static compliance and tympanometry measure mobility.
Acoustic reflexes and acoustic reflex decay give information about
probable disorders.
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WHAT WILL THE TYMP LOOK
LIKE?
TYMP
LOSS
A
Normal/Sensorineural
Presbycusis
AS
Conductive/Mixed
Otosclerosis
A
AD
Conductive/Mixed
Ossicular
Discontinuity
A
B
Conductive/Mixed
Otitis Media
A
C
Normal/Conductive Eustachian
Tube
Dysfunction
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DISORDER
EXAMPLE
PRESENT
OR ABSET
REFLEXES
P/A
P/A
Normal hearing->better than 25db with air conduction
and bone conduction equal
Sensori-neural hearing loss->hearing worse than 25db
with air conduction and bone conduction equal
Conductive hearing loss-> there is a gap of greater than
10 db b/w the air conduction and bone conduction of the
same ear at the same frequency
Mixed hearing loss->bone conduction thresholds are
worse than 25 db and there is an air-bone gap greater
than 10db in the same ear at the same frequency
SPEECH
100% - 90% - excellent
90% - 80% - good
70% - 79% - fair
Below 70% - poor
Below 40% - very poor
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Sensitivity Prediction by the acoustic Reflex (SPAR):
This is a popular test for predicting hearing sensitivity. It is based
on the difference between acoustic reflex thresholds to the pure
tones and the reflex threshold to broad band noise (BBN).
SPAR = Reflex PTA (500, 1, &2kHz) – BBN +5dB correction factor
If a SPAR value is less than 15, there is a high probability of a
SNHL. In most normal hearing individuals, the reflex threshold
for BBN is much lower than for tones. In a SNHL, the reflex
threshold for BBN is significantly higher while the pure tones do
not change. Thus, the closer the BBN reflex threshold to the PT
reflex thresholds, the greater the likelihood of SNHL. This test
may be used for children who cannot respond. It may also be
used for malingerers.
Other tests which do not involve voluntary responses are:
1. Auditory evoked potentials (AEPs)
2. Otoacoustic emissions (OAEs)
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136
Chapter 9
AEP – Auditory Evoked Potentials
There are neuroelectric events; they are measured from the scalp
via electrodes. The electroencephalograph (EEG) is used and
looks for a change in activity. All waves, except for the change
associated with the introduction of the click stimulus, are then
filtered out. They are subdivided based on where and when they
occur:
1. ECoG or Electrocochleography: this is the electrical
response generated within the cochlea. This test is used
primarily for determining Meniere’s disease. We look at the
action potential (AP), cochlear microphonic (CM), and the
summating potential (SP). Reflects activity of the cochlea and
VIIIth nerve and is the earliest of the Evoked Potentials,
occurring in the first 5 ms.
2. ABR (Auditory Brainstem Response) aka BAER (brainstem
Auditory “Evoked Response aka BERA (brainstem evoked
Response Audiometry): This occurs in the first 10 – 15 ms and
the response comes from the 8th nerve and brainstem to the
midbrain. It is the most commonly used test of the the evoked
potentials. There are 5 waves we measure. We can
approximate hearing sensitivity for high frequency click stimuli
from this. It is also a good test for neonates, and until
recently, the gold standard for newborn screening in the
screening version called is the AABR (Automated Auditory
Brainstem Response). If there is a delay of waveforms, when
using this test for diagnostics, we can guess where the
probable site of pathology lies: Wave I from the distal portion
of the VIIIth nerve where the fibers leave the cochlea (also the
equivalent of the ECoG), Wave II from the proximal portion of
the nerve near the brainstem, Wave III from the proximal
portion of the nerve and from the cochlear nucleus,
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and waves IV and V have contributions from the cochlear
nucleus, superior olivary complex, and lateral lemniscus.
These waves are referred to as Jewett Waves. Interpeak
latencies are also evaluated, I-V, I – III, and III-V. Finally, the
interaural latency difference, or ILD is looked at. This is the
difference for the same measurement between ears and should
not exceed .3msec. This test may be used to find acoustic
neuromas (vestibular schwannomas). One may assess the
integrity of the central auditory pathway using a fast rate to
find demyelinating disease (MS). Multiple components to this
may be:
a. The standard ABR – just look at absolute peak latencies,
interpeak latencies, and differences between ears
b. The Latency-Intensity Function – may obtain wave V
down to within 10 – 20dB of threshold, good for babies
and malingerers
c. Rate series: same sound and click but at different
speeds, sensitive to demylinating disease (MS).
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139
3. AMLR (Auditory Middle Latency Response) – This
originates in the midbrain and occurs in the fist 50 ms after the
introduction of the stimuli. It reflects the activity at or near the
auditory cortex. It uses tone pips and may provide information
for frequencies below 2KHz as ABR measures 2 – 4kHz. It is
characterized by 2 positive peaks, Pa at 25 – 35msec and Pb at
40-60msec after stimulus presentation. It is of questionable
use with infants and uncooperative patients. May also be used
with central auditory processing disorder. At times it may be
used for threshold determination as well.
4. LLR (late latency response) or (ALR - Auditory Late
Response) or LER (Late Evoked Response) – Occurs beyond
60ms, within the first 250msec and comes from the cortex,
specifically the activity of the primary-audiotry and association
areas of the cerebral cortex. It has a negative peak, N1, at
about 90msec and a positive peak, P2, at about 180msec after
sound presentation. At 300ms it is known as the P300. It
may assess neurological function. The patient must be alert.
Be aware that there is a developmental effect for the ALR
during the first 8 – 10 years and then it becomes robust.
The above tests may be used in intraoperative monitoring to
assess the integrity of the 8th nerve as surgery progresses. It is a
way to preserve hearing during surgical procedures. The
standard ABR or ECoG are the most commonly used tests for this.
The 4 main applications of the above are:
a. to predict hearing
b. infant hearing screening
c. diagnostic assessment of CANS function
d. intraoperative monitoring as mentioned above
140
5. STACKED ABR – this also uses clicks and high pass pink noise
masking. It is the composite of activity from all frequency
regions of the cochlea. – may screen and detect for small
acoustic tumors and may be a good estimation of threshold for
hearing for those who are difficult to test.
6. AUDITORY STEADY STATE RESPONSE (ASSR): This test
used modulated tones that can be used to predict hearing
sensitivity. It is evoked by a periodic modulation of a tone
(usually 500Hz, 1kHz, 2kHz, or 4kHz) and the potential follows
the time course of the modulation. Good for those who cannot
response normally.
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Otoacoustic Emissions Audiometry
This test is a preneural response giving information up to but not
including the auditory nerve. They are an active byproduct of the
outer hair cell system. If there is a compromise in the outer or
middle ear, the response will be affected and most likely be
absent. Remember, this is not a direct measure of hearing.
142
1. OAE – Otoacoustic Emissions aka Evoked Otoacoustic
Emissions – Most normal cochleas react to acoustic stimulation
with a very tiny sound of its own. So these are low intensity
sounds generated by the cochlea and transmitted into the
middle ear and ear canal. That is why if there is a middle ear
problem, the OAE will be absent except in the case of
ventilation tubes. This equipment is used to detect and amplify
this miniscule response. This has become a popular test for
newborn screenings. There are different types of evoked
otoacoustic emissions:
143
2. TOAE (transient otoacoustic emissions) aka as TEOAE
(transient evoked otoacoustic emissions) – These are produced
by brief acoustic stimuli such as tone pips or clicks. The
response is usually all or none. Anyone with normal hearing
and normal ear structures should have emissions. A middle ear
problem or hearing loss greater than 35 - 40dB will eliminate
the response.
3. DPOAE (distortion product otoacoustic emissions) – For this
test, 2 primary tones are presented and the normal ear
produces energy at additional frequencies known as the
distortion product. As the primary tones vary, so does the
distortion product. A response may be obtained as long as the
loss does not exceed 40 – 50dB.
4. SOAE (spontaneous otoacoustic emissions) – This is not an
evoked response. Many normal ears (50 – 70%) have natural
emissions and these may be measured. It was initially thought
that this would explain tinnitus, however, this has not proved
to be the case.
Both the TOAE and DPOAE give a measure of outer hair cell
function. That is why they are sensitive to cochlear vs
retrocochlear pathology for hearing loss below 65dBHL.
Some advantages to using OAEs over the ABR in newborn testing:
2. the test time is much faster
3. noninvasive tests that does not involve the use of electrodes
4. less sensitive to environmental noise
144
So, OAEs are applicable for the following:
a. infant screening (all or none phenomenon, sensitive to the
most minimal of hearing losses)
b. pediatric assessment – if we can only obtain sound field
results, we cannot determine if one ear is better than
another, but this would give us ear specific results easily and
without needing a response from the child
c. cochlear function monitoring – are potentially ototoxic meds
having an effect on the cochlea
d. some diagnostic cases – is the problem in the cochlea?,
outer hair cells vs inner hair cells, auditory neuropathy?
e. Also good for verifying hearing in pseudohypacusis
f. To diagnose cochlear dys-synchrony (aka neuropathy). Is
the inability to hear or discriminate words due to disruption
of synchronous neuronal firing in the auditory pathways?
This is especially helpful for early infant detection when
combined with ABR testing. If OAE only without ABR, this
disorder would have been missed.
MATERIAL FOR SECOND TEST ENDS HERE
145
Chapter 10, p. 437 – 461
Young children often cannot be tested in the same manner as
adults. The procedures used will vary, based on the age and
maturity of the child. We must be flexible and alert, able to
modify a procedure to obtain what we need. Sometimes the
response may be barely detectable, very subtle, and you must be
looking for it to see it. With universal infant screening, the
challenges we face now will often be transferred to the SLP. Our
current challenges:
 Identify the children at risk and needing further
evaluation
 Determine if there is an actual hearing loss and
differential diagnosis of the loss and quantification of
the loss
 Assess preschoolers with possible CAPD, identify,
quantify and refer
The challenge for audiologists and the SLP:
 Once these children are identified and found, what are
the referrals to be made
 Are there professionals ready to immediately begin the
necessary habilitation
 Are we prepared for the influx due to universal infant
screening. If not, all our screenings and early detection
is meaningless.
Some additional case history information, in addition to
those questions discussed earlier, might be:
1. Were there any problems during the pregnancy or birth?
If so, what?
2. Is there any history of ear infections?
3. Were the child’s developmental milestones to date
normal?
4. Do you have any concerns about hearing,
speech/language development, or general development?
146
So let’s have a brief, cursory review of language
development.
3 months: There is no difference in response to stimuli between
the hearing and deaf infant.
6 months: They go from reflexive babbling to intentional babbling
and vocal play. A deaf baby will revert to reflexive babbling if
they cannot hear themselves. If they don’t make this transition
out of reflexive babbling, they will never rise to higher levels.
Cannonical babbling: raspberries, mama, dada, change voice
This stimulates the auditory system and encourages further
development of the auditory system between the ears.
At 12 months of age they start linking words to meanings.
At 18 months of age there is one new word every 2 hours.
At 24 months of age, there are 2-word phrases.
At 36 months of age, they make short phrases.
At 30 – 36 months, they apply the rules to language and
overgeneralize rules.
Overall, the temporal lobe dominates.
In central system analysis, they look for frequency shifts to
identify speech and send it to the left hemisphere. Only speech
produces frequency transitions with the exception of computergenerated synthesized speech. Sounds determined not to be
language are sent to the right hemisphere.
So the left hemisphere is for concrete language and the right
hemisphere is for suprasegmentals and the abstract. The 2
halves together give the full reception and expression of
language.
We know there is a difference between females and males.
147
Thus, in babies, the low and mid frequency regions develop first.
The high frequency region develops after birth.
At 4 days after birth, an infant can distinguish the mother’s
language from others.
At 6 – 10 months of age, babies can differentiate phonemes.
At 6 months of age, syllable pattern recognition begins and then
comes the baby’s first word – NO!
The children learn language by shared experience. They learn
syllable patterns. This is important to brain development and the
development of listening skills.
The auditory brain map is formed by 12 months of age. An
absence of stimuli between 6 – 12 months produces a
measurable speech delay.
The most critical period for speech learning is birth – 12 months.
2nd most important period for this is 12 – 36 months.
Below 3 months
Speech and language are imitative processes, acquired mostly
through audition. A problem early on can interfere with the
development of speech and language acquisition, thus
culminating in a deficit of normal communication. Most of these
infants were referred because of high risk factors or they failed
and OAE/AABR screening.
Babbling is not indicative of anything. If anything, it will decrease
later on in the hearing impaired child. Also, a difference in vocal
quality may be noted between infants with normal hearing and
infants with hearing losses.
Until recently, our detection of children with hearing loss could
often take till 3 years of age. Yet numerous studies have shown
148
that the earlier intervention is initiated, the better the chance of a
well adjusted, good communicator.
Hearing loss has been ranked 6th in prevalence of chronic
conditions in the US. Thus, it occurs more often than many other
disorders that we currently screen for. The savings to the
government in special education and other needed services later
on more than makes up for the cost of newborn screening.
Three states, Rhode Island, Colorado, and Hawaii voluntarily
began their own programs without mandate. The biggest
problem noted is with the number of false positives.
Some, such as Luterman question:
a. Whether proper bonding with the mother can occur if hearing
is at question early on
b. if the hearing loss is genuine, every parental activity becomes a
learning activity rather than just enjoying the child
c. is the audiologist legally liable for the mental stress, especially
if it was a false positive
It has been suggested that the newborn screening methods, in
conjunction with the high risk registry, can reduce the false
positives. Our state has mandated newborn screening, however,
they are always trying to cut the budget.
10 High Risk Factors (as determined by a joint committee)
1. Family history of congenital or delayed-onset childhood SNHL
2. In utero infection associated with SNHL (i.e. CMV, rubella, etc.)
3. Craniofacial anomalies, including those of pinna and ear canal
4. Birth weight less than 1500 grams (about 3.3 lbs)
5. Hyperbilirubenemia at levels needing exchange transfusion
6. Ototoxic meds, & diuretics used in combination with the drugs
7. Bacterial meningitis
8. Severe depression at birth, including low Apgar scores
9. Prolonged mechanical ventilation of at least 5 days
10. Stigmata or other findings associated with a syndrome
known to include SN or conductive hearing loss
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Risk factors that would suggest the necessity of a
screening during the first 2 years:
1. concern regarding hearing, speech, language, &/or
developmental delay
2. bacterial meningitis or other infections associated with SNHL
3. head trauma associated with concussion or skull fracture
4. stigmata or other findings associated with syndromes known
to include SNHL
5. ototoxic medications and diuretics
6. recurrent or persistent OM with effusion for at least 3
months
It is possible that there may be some disorders with delayed
onset of HL, therefore, the following are risk factors for periodic
monitoring of hearing till 3 years old:
1. Indicators associated with delayed onset of SNHL are:
a. family history of hereditary childhood hearing loss
b. in utero infection like CMV, rubella, syphilis, herpes, etc.
c. neurofibromatosis & certain neurodegenerative disorders
2. Indicators associated with conductive hearing loss are:
a. recurrent or persistent otitis media with effusion
b. anatomic deformities or other disorders affecting
Eustachian tube function (i.e. Treacher-Collins)
c. neurodegenerative disorders
With the high risk registry, only about 50% of newborns with
hearing loss are caught because the other 50% did not have the
high risk factors.
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There have been different techniques for screening newborns
over the years:
a. cardiac response
b. respiration audiometry, alternation of sucking, and startle
response
c. crib-o-gram
d. High Risk Registry
e. ABR
f. AABR
g. ABR with High Risk Registry
h. OAE
ABR was the first real way of testing that gave better sensitivity.
When combined with acoustic reflex testing, it produced a more
sensitive and specific approach to new born testing.
Now we have OAEs. These are even more cost effective. There
is no need to use electrodes and clean the skin. It is a simple tip
in the ear and very quick. It is less sensitive to environmental
noise, making it excellent for the NICU.
Testing birth to 1 year
1. casually observe the child.
2. Personally, I like to listen to the mother. Parents know their
child and are more sensitive than most pediatricians to the
presence of hearing loss.
3. Listen to the child vocalizations. Severe hearing loss can be
detectable in their vocalizations.
4. Behavioral Observation Audiometry (BOA) in sound field
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Behavioral Observation Audiometry (BOA) 0 – 1yr
This is conducted in a sound field environment through speakers.
Speech, various noises, warble tones, etc. may be presented and
we look for:
a. cessation of activity whether it be sucking, crying, or
breathing or even eyeblinks.
b. Localization to the speaker where the sound comes from by
8 months old. Prior to that, a searching behavior should be
noted.
Some children will respond to the sound off rather than when the
sound is turned on.
Visual Reinforcement Audiometry (VRA)
This is the same as BOA, however, at this time the child is trying
to localize to the source of the sound. Localization or sound
acknowledgement is rewarded by a clapping toy or lighted toy,
etc.
Testing 1 – 5 years of age
Young children fatigue quickly, therefore you jump in and get
what you can. Before 3 years of age, the VRA is most likely to be
used. At 2, they may even repeat some words. If nothing else
works, you can ask them to point to body parts or ask questions
like “where is mommy?”. Listen to their vocalizations, if they are
almost silent, there may be hearing loss suspected.
Conditioned Play Audiometry (CPA)
By 3 – 5, you can try conditioned play audiometry. They respond
to the stimulus most often by placing a block in a box or a ring on
a post, or a peg in a hole. They may also respond to the
command “put it in”. For most, at this point, you can probably
perform this task under headphones.
Often, I can even get them to say “birdie” to warble tones.
152
For the immature or very young child or children with multiple
disabilities, when you can only obtain response through the
speakers, it is impossible to know whether it is indicative of the
better ear or both ears. That is where the OAE come in as it can
tell you if the outer hair cell activity is normal in both ears or not.
Always include your impedance measures to allow you to guess
normal, SNHL, or conductive problem.
THE CROSS CHECK PRINCIPLE
According to your book, “no single test result obtained
during pediatric assessment should be considered valid until
you have obtained an independent cross-check of its
validity”.
A recent article in Advance magazine (Jan, 2013) gave the
following article to check for possible speech delay due to
hearing loss:
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NEWS WATCH
Several Development Milestones Can Signal Possible
Hearing Loss
Posted on: January 8, 2013
Infants and young children have developmental milestones
that parents can watch for to identify a possible hearing loss.
By 3 months, your baby recognizes your voice and makes
cooing noises. Sudden, loud noises should startle your baby.
By 6 months, your baby recognizes speech sounds and
familiar noises. Interesting noises make your baby turn their
head, and your baby plays with their own voice and laughs.
Your baby also uses their voice to indicate pleasure and
discomfort.
By 9 months, your baby understands simple words like
'mommy' and 'daddy,' 'no', 'bye-bye' and their own name.
By 12 months, your toddler can speak one or more real,
recognizable word.
By 18 months, your toddler understands simple phrases and
retrieves familiar objects on command and speaks between
20 to 50 words and short phrases and your toddler learns
new words each week.
By 24 months, your toddler's spoken vocabulary should be
200 to 300 words and simple sentences can be spoken.
Adults who are not around the child on a daily basis can
understand your child's speech. A toddler at this age should
also be able to sit and listen while being read books.
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Central Auditory Processing Disorder (CAPD) aka APD
Central Auditory Processing: May be involved in the
following:
 Sound localization
 Separation of signal from noise
 Detection of signal in noise
 Preprocessing for pattern identification
 Providing the foundation for concrete language
 Processing the abstract portions of language
CAPD: children whose recognition or use of language is not
age-appropriate, and/or is inconsistent with their level of
intelligence. Many of these kids also have learning disabilities
which prevent them from being able to progress normally in
their education. It should be noted that CAPD measures are
very sensitive to the effects of attention.
Language delays may occur due to:
 Hearing
 Drugs/alcohol
 Environmental
 And high frequency hearing loss can be responsible for
language delay
Most of these children have normal peripheral hearing. While this
has become a catch-all category, many symptoms of CAPD
include:
 poor listening skills
 easily distracted
 slow responsiveness
 articulation disorders
 language delay
 short attention span
 poor memories and reading comprehension
 difficulty in linguistic sequencing
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 problems in learning to read and spell
 difficulty recognizing speech in the presence of background noise
Some auditory processing symptoms in social behavior might be:
- Hyperactive
- Fatigues
- Lethargic
- Disruptive
- Withdrawn
- Poor memory
- Passive
- Slow Starter
- Fail to complete task
There is no particular behavior for a child that classifies them as APD.
As can be seen, many of these symptoms overlap with:
- ADD
- LD
- Speech/language disorders
- Behavior disorders associated with
 Fine motor coordination
 Visual Disorders
A more structured learning environment can be very helpful for
these children.
The speech tests administered in CAPD will be more challenging
than standard tests. These usually are words or sentences
presented with competition, both ipsilaterally as well as
contralaterally.
Hearing loss and/or CAPD can have an effect on social,
intellectual, and emotional development.
Some of the effects may include egocentricity, difficulty in
empathizing with others, rigidity, impulsivity, coercive
dependency, and a tendency to act up.
Auditory Processing Therapy:
 There may be environmental manipulations
 One to one contact
 Personal FM system
 Preferential seating
 Multi-modality input
 Manipulations of temporal/spectral characteristics of sound
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Decrease presentation velocity for improved processing
then gradually increase presentation velocity
“Velocity”
Memory exercises
There have been articles on the importance of Music in assistance
of development of the right side.
 Development of spacio-temporal reasoning
 ? development of math skills
 ? development of pattern analysis
 ? perception of meaning
Music, math, and logic may be connected.
The neurons are exercised by music. This strengthens the same
circuits used for mathematical reasoning. Therefore,
preschoolers taking piano or singing lesions improve spatial
reasoning. The melody must be identifiable however.
Children with developmental disability are tested by whatever
means we can.
In the public schools, children are typically screened every other
year. It is not perfect and there is an inverse relationship
between efficiency and accuracy in any screening procedure. It is
also true that the environment in which the screening is
performed is less than perfect and often we raise the pass values
at 500Hz to allow for the excessive noise.
Now, with so many more infants and children being detected, we
really need the personnel with training and programs in place to
adequately service these infants and children in order to:
1. facilitate speech and language development
2. properly counsel parents and give unbiased information of all
possible educational routes that can be taken
3. provide support programs
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4. mitigate some of the psychological consequences of hearing
loss on the child and the family.
The current climate has moved from a client-centered medical
model to a family-centered model. In the latter, the family must
be educated and empowered to work as a co-partner in
planning strategies for their child.
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Chapters 12, 13, 14 Management of Hearing Loss
Some type of aid to hearing has been utilized throughout
history, ranging from animal horns and seashells to ear
horns, even using a hand cupped behind the ear. Whether
these primitive methods, or more modern hearing aids, they
all collect and direct sound energy.
19th century – first electronic hearing aids – they were huge!!!!
Reading the history of hearing aids is like a delayed history of
electronics, there were:
Carbon hearing aids that were body worn
Vacuum tube aids allowing for more power and smaller aids
Transistors, further miniaturizing hearing aids and completely
replacing vacuum tube aids.
Now we have integrated circuits.
Even better, we have computer technology!!!!
This is also known as digital signal processing.
Now, even more, we have WIRELESS CONNECTIVITY!!!!
Rule of thumb for fitting one or two hearing aids:
1. if all is symmetrical, both hearing and speech discrimination,
fit both ears
2. if asymmetric and both ears have good speech
discrimination, try fitting both ears
3. if asymmetric and speech is much better in one ear than the
other, fit the ear with better speech discrimination
4. if symmetrical but speech is much better in one ear than the
other and other issues have been ruled out, fit the ear with
better speech discrimination
5. if asymmetric and there is a severe to profound loss on the
bad side, fit the good side only
6. if profound loss bilaterally with poor to no speech
discrimination, consider referral for cochlear implant if used
to be part of hearing world, otherwise leave in Deaf Comm.
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Hearing aids consist of a microphone, amplifier, and receiver and
are used to amplify sound and deliver it to the user’s ear. Sounds
strike the microphone (input transducer), are amplified, and
transmitted to the output transducer (receiver or loudspeaker)
and into the external ear canal. For those for whom, for some
reason, a standard hearing aid cannot be used, a bone
conduction hearing aid may be feasible. Reasons for not being
able to use standard hearing aids may include atresia, stenosis,
chronic middle ear drainage, perforation, dermatologic problems,
etc.
Hearing Aid Circuits
So hearing aids are signal processors, they alter the signal input
to improve it for the wearer. Types may include:
Analog Hearing Aids: similar to an LP, the waves coming out
are like those going in. They modify a continuous electric signal.
Fine tuning is very limited to the type of circuit.
Hybrid Hearing Aids (Programmables): These use both
analog and digital technology. They shape the sound digitally but
use analog processing. While more precise in fine tuning than
the analog aids, they are not as fine tunable as the digital aids.
Digital Hearing Aids: These are the newest. Sound waves are
converted to binary digits (computer talk using 0’s and 1’s) much
like data storage. It changes the output via analog-to-digital
converter. Advanced processing operations can then be carried
out and the altered signal changed back to analog form by the
digital-to-analog (D/A) converter. They provide improved clarity
of signal and better signal to noise ratio. They may separate
wanted sound from unwanted sound but are still not perfect.
They also allow for more fine tuning than ever before.
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Electroacoustic Characteristics of Hearing Aids:
1. Output Sound Pressure Level: the maximum sound
pressure the hearing aid can produce at high input levels. Also
known as saturation sound pressure level. This is especially
important in the case of babies. Failing to be careful may
cause a noise-induced hearing loss if there are dangerously
high sound levels.
2. Frequency Gain: this is the difference between the input
signal and the output signal. For example, if a signal of 60dB
goes into the hearing aid and 110dB comes out of the hearing
aid into the ear, then 110 – 60 = 50dB of gain. That is the
amount amplified to get the output.
3. Frequency Response: The range over which the hearing aid
provides amplification. With advances in technology, we can
cover a wider range of frequencies. The microphone and
receiver of the aid are the prime limiters of the frequency
range. With today’s hearing aids, we can set the response for
each hearing loss specifically.
4. Distortion: This occurs when the sound leaving the hearing
aid is very different from what went in. It reduces clarity and
intelligibility. Most common is harmonic distortion. The
greater the distortion, the poorer the quality of amplified
speech.
5. Input-Output Characteristics: describes how the hearing
aid functions at different loudness levels. Tells how much the
amplification is increased with increase in the input signal. You
can see if this is linear or nonlinear. Unless the loss is sever to
profound, almost all amplification is nonlinear.
6. Compression, Peak Clipping, Output Limiting, Wide
Dynamic Range Compression (WDRC), Automatic Gain
Control (AGC): There are additional parameters that limit the
output of the hearing aid as sounds gets louder to avoid
peaking at an individual’s uncomfortable listening level.
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All the above are measured in a test box with a 2cc coupler. We
can also measure some of these characteristics in the individual’s
ears using a probe microphone system. This may also be used as
a verification of your fittings.
A more subjective method of verification could be obtaining
function gain:
Functional Gain: This is similar to acoustic gain. It is
measured by obtaining hearing levels in sound field without the
hearing aid and with the hearing aid. May be done with warble
tones or speech.
This allows to show how much gain the individual actually
perceives when using the hearing aid and their improvement as
compared to how they do at the same level without the hearing
aid.
The validation, which may be defined as a determination of
whether the disability has been reduced and goals addressed, may
be established through clinometrics, or questionnaires/scales.
Another method of establishing you fit the individual properly is
Probe-Microphone Measurements and Speech Mapping.
Real ear Gain, measured by probe mic equipment, shows us the
amount of gain delivered to the ear directly. A loudspeaker is
placed close to the patient’s ears, a thin tube inserted into the ear
canal close to the TM and attached to a mic. Sounds are
presented out the speaker and the hearing aid response in the
patient’s ear is recorded.
With Speech Mapping, ongoing speech is presented via the probe
mic at a fixed level and the output displayed. The hearing aid
parameters can then be adjusted as needed.
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Parts of a Hearing Aid
1. The microphone – in addition to what was stated earlier, we
now consider whether we will be omnidirectional (sensitive
to sounds from everywhere), or directional (sensitive to
sounds in front of a person), directional fixed or automatic
directional adaptive (comes and goes as needed for noise
and sensitive to sounds from where the speech comes)
2. The amplifier – controls how much amplification occurs at
different frequencies, may boost sounds differently, and
may be able to limit sound from becoming too loud. (The last
used to be known by many names over the years including
output limiting, peak clipping, compression limiting, etc).
3. The receiver – also considered the loudspeaker and it is a
transducer that changes electrical energy back to
acoustical energy. With RIC or RITE hearing aids, the
receiver is placed in the ear canal itself rather than being
part of the body of the hearing aid.
4. Potentiometers – these are screwset controls, present on
old analog hearing aids and some of the older programmable
aids, to set high and low tones, limit loudness, limit gain.
We no longer need this as things are adjusted by computer.
5. Remote Controls – not available for all hearing aids but
many manufacturers have optional remotes for adjusting
volume, program, or wireless connectivity.
7. Manual Controls – Older hearing aids have an MTO
(mic/telephone/off) switch. Even some digitals have a
pushbutton control or toggle to change volume or program.
8. Battery door – found on all aids except disposables, some
current manufacturers offer to charge batteries while in
the hearing aid
9. Earhook (on standard BTEs) – where earmold connects
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10. DAI – Direct Audio-Input, usually at the battery door of
a BTE so other systems such as FM can be connected
11. Earmold – a part that attaches to the BTE earhook to
send the sound into the ear. Sometimes also used with
RIC/RITE hearing aids.
12. Auto T – much more common now, and option which
allows a hearing aid to go into telephone mode without having
to move any switches on the hearing aid or hit anything on the
remote control.
13. Ear Domes – the disposable tips that fit the end of the
RIC/RITE/thin tubes in the ear canal
14. Color options
15. Connectivity – special remotes and other parts to change
televisions, phones, iPods, etc into Bluetooth devices for
the hearing aids (i.e. Oticon Streamer, Siemens Tek, Phonak
iCom, etc) Now there is even a mic for others to talk into
and sent via Bluetooth without getting a FM system.
16. noise/feedback reduction – most use noise cancellation
technology today so feedback is not the issue it used to be.
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EARMOLDS
An earmold can change the acoustics or frequency response of
the hearing aid. This is known as earmold acoustics. There are
different types of earmold and various degrees of venting.
Styles of earmolds
The earmolds block the ear canal to various degrees. High
frequency hearing losses use open earmolds that do not fully
block the canal. The more severe hearing losses use earmolds
that fully seal the ear canal to prevent sound leakage that cause
feedback from high power hearing aids. See figure 13-18 for
examples of 3 types of molds.
Venting
A vent is nothing more than an opening in the mold that allows
air and sound to escape. Depending on the loss, it will vary in
diameter. Most commonly is the SAV or select-a-vent that allows
the fitter to vary the diameter by using plugs with varying
diameters. The vent usually runs parallel to the channel
containing the tubing. It would be minimal for severe losses and
large for minimal losses.
Horn Effect
The horn effect can increase the high frequencies. One way is to
use a Libby horn which is a tubing that increases from 2mm to
3mm or 4mm going into the mold. Another way to obtain this is
to widen the bore at the end of the mold or “bell” the bore.
Damping
This may be a filter or piece of damping material that is placed
into the earhook of the hearing aid or into the earmold to
decrease and smooth out peaks in the amplitude of the hearing
aid response.
Venting, horn effect, and damping all affect different portions of
the frequency response. They are affected in the following
manner:
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Venting Damping Horn Effect -
low frequencies
mid frequencies
high frequencies
There are now special molds made by most labs to work with the
RITE/RIC and special high power canal molds for the power
RITE/RIC hearing aids.
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Types of Hearing Aids
Body Aids (used with earmolds)
Eyeglass hearing aids (used with earmolds)
Behind-the-ear (BTE) hearing aids (used with earmolds)
OTE open ear fit RITE/RIC
OTE open ear thin tube fit
In-the-ear hearing aids (ITE)
Half shell hearing aids
In-the-canal hearing aid (ITC)
Completely-in-the-canal hearing aids (CIC)
CROS and BiCROS hearing aids
Bone-conduction hearing aids
Implantable Bone Conduction devices/BAHA
Middle ear implants
Cochlear implants
Auditory brainstem implants – for NF2 patients – can’t use
CI so implant electrode in brainstem and an external sound
processor sends electrical stimulation to the auditory
neurons of the CN, hoping to improve the client’s ability to
detect or understand incoming speech information
 Vibrotactile devices (ie tactaid)
 For the future: completely implantable hearing aids
 Hair cell regeneration
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Discuss why 2 are better than one –
Directionality – The left and right location is determined by
perception of the difference of arrival time or difference in phase
of sounds at each ear. If there are more than two arrivals, as in
a reverberant environment, we choose the direction of the first
sound to arrive, even if later ones are louder. Height information
is provided by the shape of our ears. If a HF sound arrives from
the front, a small amount of energy is reflected from the back
edge of the ear lobe. This reflection is out of phase for one
specific frequency, so a notch is produced in the spectrum. The
elongated shape of the lobe causes the notch frequency to vary
with the vertical angle of incidence, and we can interpret that
effect as height.
When both ears are amplified, the sound from each ear fuses
together at the level of the brainstem giving about 3dB increase
in gain as compared to one (binaural summation) and so there is
more usable gain.
When both ears are amplified, the brainstem can separate speech
information from background noise better (background squelch)
Localization is improved with a binaural fit due to 2 ears working
with time and intensity cues from the arrival of sound to each ear
as explained above.
Finally, if a hearing aid is worn in one ear, then sound from the
other side is not amplified in the unaided ear and the head
shadow effect causes the gain to be reduced in the aided ear.
Exercise both sides of the brain
What else?
No need to turn the head
Discuss reasonable expectations.
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There are other devices to aid in listening besides hearing aids.
These are mostly termed Assistive Listening Devices or ALDs.
These include:
- FM systems
- Personal amplifiers (Pocket Talker)
- Closed captioning
- Infra-red systems
- Amplifying headsets
- Personal sound field amplification systems
- Large room sound field amplification systems
- Amplified telephones
o built in amplifiers
o portable amplifiers
- TTY/TTD and relay services
- Cap-Tel
- Caption Call
- Video Remote Access
- Sign language interpreters
- Hearing dogs
- Voice recognition technology
- Alerting devices: Vibrating, blinking, flashing, beeping
devices for alarm clocks, doorbells, smoke detectors,
baby-crying detectors, etc.
- Bluetooth device connection is here now
- CART
- Notetaker
These devices may be used in addition to or in place of hearing
aids. They may make an individual’s life easier, improve the
quality of life, improve relations with the family, and give more of
a feeling of independence.
For example, the individual who can use a phone amplifier, no
longer needs to depend on someone else to answer the phone.
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Another example is the mother who can use a vibrator alert to let
her know her baby is crying.
The deaf person who can wake up on their own by using a bed
vibrator connected to the alarm.
They allow for the security of knowing you will wake up in the
event of a fire alarm, even if you are sleeping by using blinking
lights, vibrators, etc.
This independence also allows for empowerment!!
This independence may also allow protective parents to let go!!!
Let the kid be a kid!!!!
And we can all expect this to improve quality of life!!
In the future, a way to ensure compliance of treatment and
verification/validation of treatment results may be via the idea of
TELEMEDICINE. It is gaining in use across the country. With
telemedicine, treatment or therapy is conducted via computer and
monitors and cameras and even testing can be performed in this
manner. The individual performing the testing/therapy MUST be
licensed both in the state where they are conducting therapy from,
as well as in the state where the patient resides. In this state,
they are still trying to decide on what to write into the licensure
law and/or rule and treatment is only going to be within the state.
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ADULTS
The US Census Bureaus has shown that those individuals 65
years of age or older is the fasted growing segment of the US
population and so the need for audiological services will be large
as such a high percentage of the elderly suffer from some degree
of hearing loss. Some of the natural changes in the body include:
a. outer ear: loss of cartilage elasticity, perhaps resulting in
collapsing ear canals
b. middle ear: arthritic changes causing stiffness of ossicles
and/or tympanic membrane
c. inner ear: sensori-neural hearing loss, especially of high freq
d. 8th nerve and neural processing: these changes may include
degeneration of the auditory nerve, brainstem, and auditory
association areas of the brain, thus compromising the ability
to understand, especially in noise, and compounding the
peripheral changes discussed above. These changes are
changes due to the aging process, aka senescent
changes, and counsel appropriately. Be aware of the
hassle factor. Depending on lifestyle, for some of the
elderly, a hearing aid may be more trouble than it is worth
and an assistive listening device would be more appropriate.
In some cases, these elderly develop problems similar to
very young children, such as CAPD. The loss of vision
further compounds these issues as they do not have the
assistance, whether consciously or unconsciously, of
lipreading or reading facial expressions.
Although the goal is to reduce hearing handicap by maximizing
the use of residual hearing, approaches to reach that goal may
vary from patient to patient.
We must look at age, type of disorder and patient need.
We must ease the burden on listening in noise.
We must consider other needs; emotional, educational,
psychosocial, and the effects on interactions. Much of this can be
found via our assessment scales/questionnaires.
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Audiological Rehabilitation: management of these patient; aka
Aural Rehabilitation. If you get someone at birth, rather than
rehabilitation, you use habilitation since there was nothing to
rehabilitate.
The goal of adult AR is to make maximum use of residual hearing
and they may need more help than would be thought based on
the test results. The broader their dynamic range (the range of
sounds they can tolerate), the better they will probably do.
Combine audiometric data and questionnaires/scales to determine
an individual’s impairment, handicap, and needs.
So aural rehabilitation is more than speechreading.
Counseling = LISTENING = uh huh
Know when the problem has become pathological and when the
counseling needed is beyond your scope of practice and don’t be
afraid to REFER.
Be there with the individual, watch your body language, give
them what they need, not what you think they need.
Do not use the medical model – you are the boss and tell the
patient what they are to do, authoritative
Use the client-centered model – you discuss and conclude
together, everything is collaborative.
It is best to include the entire family, including significant others
and caregivers.
Give orientation individually or in groups or some combination
thereof. The environment may be in the traditional setting of a
professional office or a home, senior center, house of worship,
ALF, etc. may be used as well.
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Teach them to maximize communicative skills by managing
environments. Train the patient with hearing loss in maximum
use of residual hearing.
One aural rehab consideration is a new, interactive, computerbased tool called LACE (Listening and Communication
Enhancement) It provides both interactive and adaptive tasks.
By adaptive, we mean that the user’s responses determine the
level of difficulty of the task and as they improve, there are more
difficulty stimulus items. The 3 main areas addressed are
a. degraded speech – in this category, tasks are designed
to help develop better skills when listening to speech in
noise and when listening to fast speech
b. cognitive skills – These activities give short and longterm memory training and improve processing speed
c. communication strategies – these tasks are designed to
help clients develop skills to improve performance in
daily communication situations
Look for support groups for those you work with.
Family
Parents
Teens
Siblings of the HI
Grandparents
Late-deafened adults, etc.
EMPOWER
With children, the management will differ, depending if the loss is
prelinguistic or postlinguistic.
Parents reactions: Refer to Kubler-Ross – major grief and denial,
then on to anger, guilt, bargaining, and finally, acceptance.
Don’t forget to recommend genetic counseling.
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Prelinguistic:
You need to train them as to what sounds are.
Begin speechreading early in life. Encourage them to watch
faces. Some educational beliefs do not encourage this.
Some believe that humans are lazy and will do whatever is
easiest. Manual communication and visual cues are easiest and
there will never be a total dependence on audition if you start
with anything else. Others feel that it is more beneficial to just
get that communication going, keep the frustration down, and let
them feel the ability to communicate with others.
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Before beginning educational options, we first need to look at the
basic laws:
THE AMERICANS WITH DISABILITIES ACT (ADA) OF 1990
This law applies to all ages. It provides comprehensive civil rights
protection and prohibits discrimination to individuals with
disabilities in the areas of
Title 1 employment,
Title II public services (state and local government services
including education)
Title III public accommodations
Title IV telecommunications
Title V miscellaneous
INDIVIDUALS WITH DISABILITIES EDUCATION ACT (321 - IDEA PL 94-132)
This ensures for identification and habilitation services for
children 3 – 21, including speech, hearing evaluation, counseling
and guidance, and educational adjustments/specialized services.
Within this portion of IDEA, each student gets an IEP or
individualized education program.
IDEA
Part B (3 – 21 years)
Ensures early services for the children 3 – 21 years and address
identification, evaluation, and rehabilitation of hearing loss.
Utilized the IFSP or individualized family service plan.
Part C (birth – 3 years)
Ensures services birth through 3 and may provide the hearing
aids for the child if no other insurance coverage. Also works with
parents.
SECTION 504 OF THE REHABILITATION ACT OF 1973
This section applies to all students who do not quality for services
under IDEA. If a child with hearing loss does not meet the
eligibility requirements for special education services under IDEA,
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provision of adaptations to or modification of regular education
services to support the student’s academic performance under
this section can be explored.
IDEA and Section 504 of the Rehabilitation Act address numerous
issues, including but not limited to: FAPE, LRE, compliance and
enforcement, protection for parent’s rights, evaluation,
reevaluation, composition of multidisciplinary team,
documentation, due process, etc. While an assistive device such
as FM may not be sent home under IDEA, it may be sent home
under Section 504 if needed to complete homework assignments
(i.e. FM system so they can listen to the television documentary
for an assignment).
Educational Options
Oralists: emphasis is placed on speech and amplification is
designed to take advantage of residual hearing.
Some methods are:
a. Auditory-Verbal approach (uses only audition and
amplification)
b. Aural/Oral Method (auditory and speech reading; child’s
output is oral
Manualists: communicate by sign and finger spelling
Some methods are:
a. ASL – American Sign Language – different grammar than
oral English. Communicates concepts rather than
individual words, uses facial and body movement and is
processed spatially
b. Cued Speech – enhances those speech sounds that are
difficult to differentiate
c. Finger Spelling – this preserves rules of grammar and
syntax
d. Manually Coded English (MCE) – Signs correspond to
English words and syntax is the same, includes Seeing
Essential English and Signing Exact English)
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Mainstreaming: Children spend their entire day in a regular class
except for times to received support services related to their
disability. They are entitled to the “least restrictive environment”,
however, this is not the right choice for all children.
Inclusion: Children are in a regular classroom but may have an
individual to assist them to keep on target.
Self-contained Classroom or Day Classes: children are in a class
for the hearing impaired and attend a regular school equipped for
this class.
Total Communication: This method uses all modalities and may
occur in any educational setting.
Depending on the educational method used and school attended,
some ALDs might be appropriate. Some ALD examples are FM
systems, FM mini speaker systems, infra-red systems, vibrating
watches, a sign language interpreter, etc.
Educational terms to be familiar with
IEP: individualized education plan
IFSP: individualized family service plan – educate parent to make
the decision
IDEA: Individuals with Disabilities Education Act
Section 504 – Part of ADA and applies to those who do have an
IEP
Part C – for those found to be significantly hearing impaired
under 3
Part B – for those over 3
Review Deaf controversy
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Issues of vertigo and tinnitus have not been reviewed in detail.
We touched more on the vertigo portion during the disorders.
However, be aware that most individuals with hearing loss also
experience some degree of tinnitus. Tinnitus may be defined as a
noise that is perceived in the ear or head that does not come
from any external sources. It can be very debilitating. Some
causes for this condition may include:
- ear surgery
- ototoxic drugs
- aging
- noise exposure
- head trauma
- reduced blood flow
- Meniere’s disease
- tumor
- otosclerosis
- cerumen
Some of the devices and treatments available for tinnitus are:
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tinnitus maskers – devices that look like hearing aids and
emit a noise to cover over their tinnitus
noise generators – similar to tinnitus maskers but more
broad-band noise and go to mixing point where they hear
both, their own sound and the noise
Tinnitus Retraining Therapy – This mixes using noise
generators and directive counseling and may take up to 18
months to give full relief
Neuromonics Oasis – a new device from Australia using music
with underlying noise & takes about 6 months for treatment
Hearing Aids – Often, just the use of hearing aids for those
with hearing loss will help the tinnitus.
Sound Oasis – A homeopathic device with different sound
cards including environmental sounds for sleep/relaxation and
a card with sounds for tinnitus; often helpful during the
evening for those suffering from tinnitus or to help get to
sleep.
Progressive Tinnitus Management (PTM) – created by Jim
Henry of the VA. It looks at sounds an individuals likes for
distraction, interest, and background and tries this before
going toward expensive devices.
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
The Inhibitor – a handheld device which emits an ultra high
frequency sound for one minute to temporarily inhibit tinnitus
 Combination HA/Masker Devices – This is a hearing aid which
permits a concomitant noise. As of the writing of these
notes, two manufacturers had devices for amplification and
tinnitus and two other manufacturers are about to get into it.
 PAXX100 – customized audio device to be used daily using
customized acoustic enrichment sounds. As with all other
devices, the objective is to beat the link between the tinnitus
and sympathetic nervous system so the user’s consciousness
and attention is not to the perception of their tinnitus.
 SoundCure Sernade Solution – This device looks like an iPod
as does the Neuromonics and uses “S” tones, their
proprietary sound along with options for narrow band noise
and broad band noise as a noise therapy.
There are many other treatments that have been and are being
investigated which include drugs, cold laser, biofeedback, and
even some brain surgery, however, the above are the most
common and noninvasive.
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First, let’s discuss the basics of microbiology that leads us to:
a. how germs are spread from one person to another
b. how infections are spread from one person to another
INFECTION
Microbes
1. Pathogenic versus opportunistic: we usually think
about pathogenic, HIV, Hepatitis B. They are inherently
pathogenic organisms that make humans sick when they
come in contact. The other part of infection control deals
with opportunistic organisms. That is, those organisms that
are supposed to be there, they live with us, they live on us,
and they could make us sick by their absence. These
opportunistic organisms are capable of causing disease if we
give them the opportunity and generally we give them the
opportunity by some deficiency in our immune system.
Audiologists usually deal with people at 2 opposite ends of
the age continuum:
a. We deal with young children with underdeveloped
immune systems
b. We deal with older adults whose immune system
begins to wear out as they continue to age.
Because of this, our daily patient population is much more
vulnerable to opportunistic infection than the general
population. This is significant if the first AM patient is a
50 year old health male and the 3rd is an 80 year old
diabetic female with a compromised immune system.
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2. Mode of Transmission (Vehicle): How germs are spread
from one person to another. There are 4 common modes of
transmission.
a. Contact: the most prevalent form of transmission of
germs. There are 3 types:
i. Direct: spread of germs between people by touch.
May occur from handshakes to pulling the ear back.
ii. Indirect: germs are spread via inanimate objects or
surface, i.e. countertops, armchairs, etc.
iii. Droplet: occurs as we talk, cough, sneeze, etc.
Droplets of moisture are sent from our respiratory
system into the air and the droplets of moisture contain
little microorganisms that live in our bodies and our
head is usually close to the patient and you may
exchange respiratory droplets with those patients.
b. Vehicle: this may be from food, water, blood, or other
body substances. Pathogenic and opportunistic
organisms may be transferred through blood but ear
drainage (mucous) and cerumen can be potentially
infectious bodily substances. The dangerous thing
about cerumen is that because of its color and viscosity
and the overall nature of that substance, it is difficult to
ascertain whether or not that particular substance is
contaminated.
c. Airborne: This is the sum total of all the things we put
into the air. The respiratory droplets, the heating and
cooling system, walking on carpet, all join together.
Remember, what goes up into the air eventually settles
down on surfaces and objects. So we need to regularly
clean surfaces, whether or not they need it.
d. Vectorborne: Not very pertinent to this discussion
but this is where organisms are spread from one
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person to another via a vector. A vector is an insect or
small animal (e.g. lyme disease and ticks, malaria and
mosquitoes).
3. Route (pathway): This is how organisms enter the body.
The most common routes are the normal body openings,
eyes, ears, nose, and mouth. They are normal body
openings. But the ears are connected via the Eustachian
tubes to the rest of the respiratory tract, the possibility for
an organism to come from outside the body, find its way
into the middle ear through the Eustachian tubes and into
the respiratory tract is a very real possibility. This is possible
with small, microscopic teas and fissures on the TM that you
cannot even see. You can create a body opening through
nicking, cutting, or scratching the patient through cerumen
management or impression taking. So you can crate a route
or pathway allowing the organisms in to cause infection.
INFECTION PROCESS
There are 3 criteria which determine whether or not the invading
organism will make us sick:
1. Virulence: This relates to how quickly our body can identify
the organism, create the troops to kill the organism, and get
rid of it. That virulence is also related to how quickly that
organism can reproduce in us. If we don’t identify it quickly
and it reproduces very quickly, then it can make us sick
quickly and it is a virile organism.
2. Titer (number): This is the number of organisms you’ve
been in contact with. The titer being the overall number
you are spreading from 1 person to another and is directly
related to
a. when was the last time you cleaned your hands
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b. when was the last time you disinfected the specula
c. when was the last time you cleaned the hearing aid
All of these will have a dramatic impact on the titer or the
number of germs that are available for infection.
3. Resistance of the Host: An intact immune system is very
good at fending off organisms but our immune systems
aren’t always intact. As we age, the immune system goes
down and when we are very young, it is underdeveloped.
Then there are various states of health based on how you
take care of yourself.
Looking at these 3 points:
a. you have no control over the virulence
b. you have some control over resistance of the host (take
care of yourself and vaccinate)
c. BUT YOU HAVE THE MOST CONTROL OVER THE
TITER!!! And this becomes the basis for an infection
control program.
The basic premise of an infection control program is to:
Reduce the number of pathogens in the environment to a
level where the normal resistance mechanism of the body
may take over and prevent infection.
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There are a couple of important points from this definition. We
talk about reducing the number of pathogens in the environment,
not eliminating them. Reduce them to a point where the normal
resistance mechanism of the body can take over and resist
disease. The resistance mechanism fluctuates. Protect the
individual who is the most vulnerable person in your practice.
Based on this premise, the definition for an infection control
program is:
An organized effort to manage one’s environment in
order to minimize exposure to pathogenic microbes
that can make you or your patients sick.
The key point here it that it is an organized effort. An infection
control program is an effort where you actually commit it to
paper, not just because OSHA requires a written infection control
plan on the premises, but also because of the fact that if you
write it down, you have the document that you can teach new
people from, you can monitor it, and you can train the staff every
year.
Why do we need to do this? There are 4 main points:
You deal with patient with compromised resistance
because of the nature of the practice
Procedures you do require patient contact. They require
face to face contact and you actually have to touch the patient
during the procedure
There is a potential for exposure to bodily fluids, whether
ear drainage, blood, cerumen, incontinence, droplets from the
mouth, etc.
There may be changes attributable to AIDS. Now life is
prolonged but the drugs may be ototoxic. With greater interest in
quality of life and hearing aids, there is a higher chance of seeing
such a patient.
What are the risks?
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1. A risk to your personal health
2. a risk to your patient’s health
3. a risk to your practice’s health if illness always occurs after
leaving
4. legal implications (malpractice)
5. regulatory (OSHA): OSHA’s bloodborn pathogens applies to
audiologists and speech pathologists and failure to comply
puts you at regulatory risk from OSHA.
Specific Health Concerns:
1. HIV, HBV, CMV
a. HIV – difficult to contract
b. Hepatitis B: Transferred by blood to blood contact through
saliva and the human bite. It is scary because many with
this problem never show symptoms and so it doesn’t show
up on a history form
c. CMV: there is concern with this due to the fact it generally
leads to central nervous defects. The most common is
hearing loss in unborn children. We get exposed when we
see these children. The most dire consequences occur
during pregnancy.
2. TB, Flu, colds
a. TB: WHO thought this would be gone by Y2K and it isn’t. It
is now at epidemic proportions around the world.
b. Flu: an airborne disease that is transmitted via respiratory
particles. For many we see, this can be life-threatening so it
behooves us to look into flu shots.
c. Colds: you can reduce this by simple things like washing
your hands.
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3. Fungal/Bacterial Transmission
This is probably the least severe but most common form of
infectious situation. You can transmit this through the
handling of hearing aids and earmolds. As the ear is the
“greenhouse of the body”, it is the perfect place for growing
organisms. They are usually kept in check by our immune
system. But as you change the PH of the ear canal, it
becomes vulnerable and the organism prolific. They can
spread and cause otitis externa. The organisms can colonize
on the hearing aid and earmold and then when you handle it,
you can transmit them as well. So disinfect hearing aids and
earmolds carefully before handling them. Always wash hands
before and after patient contact and handling of hearing aids.
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Basic Tenets of Infection Control
1. Environmental (do not use the following 3 words
interchangeably)
Clean: you remove the gross contamination from an
object or surface. You may or may not be killing
germs. You do this to everything. Remove the gross,
visible contamination.
Disinfect: You kill a specific number of germs. The
number killed is related to the level of disinfectant you
are using (household or hospital). EPA is the
regulatory body that oversees the marketing and
distribution of disinfectants. Data must be submitted to
the EPA of germs and amounts needed to kill germs.
The disinfectants are graded from household to hospital
grade disinfectants. Hospital disinfectants kill more
germs in less time. Use a minimum of a hospital grade
disinfectant. You can soak things in an ultrasonic
machine, use wipes to clean and disinfect, or use
brushes to clean and disinfect with spray, wipes, or
soaking.
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Sterilize: You kill 100% of the germs 100% of the time.
You not only kill the vegetative form of the germ (form
capable of reproducing) but also the spore form of the germ.
When organisms are challenged, you throw chemical on
them, you put heat on them, and they have the ability to
revert to a spore form and this is more resistant than the
vegetative form. However, that organism is constantly
trying to get back to the vegetative form of life. So when
you remove the challenge, it reverts to the vegetative from
where it can reproduce. Sterilize means killing all of them,
including spores, 100% of them 100% of the time. You
sterilize everything contaminated with bodily substances or
any object capable of breaking the skin.
i. autoclave: this is the preferred method of
sterilization, it is heat or pressure. This is not a good
one for us.
ii. chemclave: a large chamber that is capable of
handling things vulnerable to being melted because it
uses a chemical bath and a gas to kill the organisms.
They are expensive to acquire and maintain and thus
impractical for us.
iii. gluteraldehyde: this is cold sterilization. It is a
sterilant in the 2% concentration or greater but not
ideal. It is toxic and carcinogenic. Now you may use
SPOROX as an alternative.
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2 . Human
A. Hands: The single most important thing you can do to
control the spread of infection and disease in
your practice is to WASH OUR HANDS and do it before and
after every patient. You can used soap an water or “NoRinse”. If you use soap, use liquid soap as soap bars
attract germs and if creamier, it will moisturize. The germkilling action is the rubbing.
B. Gloves: this is an important of any setting and you will
want these in a number of instances. If you cannot use
latex or are allergic, use vinyl.
C. Eyes, Mouth, Nose: these are common routes for
pathways into the body so be careful. Don’t eat where there
is patient contact and wash your hands first. Don’t touch
contact lenses. Cover your nose and mouth when you
sneeze and cough.
D. Medical history: do this from an infection control
standpoint. Write not only what they are being treated for
but what meds they are taking and look them up.
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SURFACE DISINFECTION
This is a 2-step process. You must first:
a. clean to remove the gross contamination and then
b. disinfect to kill germs.
Areas to be disinfected are:
1. Counter tops, chair arm rests in all rooms, all tables, etc.
2. The lab area after working on devices.
3. The reception counter in the morning, at noon, and at closing.
Note that some products that both clean & disinfect. You
should:
1. Choose a hospital-grade, EPA registered, disinfectant/cleaner.
2. Spray or wipe the surface with the disinfectant/cleaner. Wipe
away all gross contamination with a paper tower or coarse
brush if needed.
3. Spray or wipe the surface again and leave it wet to the time as
specified on the label. It is during this dwell time that germs
are killed.
4. When there are multiple items, they can be disinfected in the
ultrasonic machine.
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WAITING ROOM AND MOTIVATIONAL TOYS
Most toys in the waiting room as well as those used for
conditioning audiometry in the booth end up in children’s
mouths or are touched with hands wet from saliva. This is
a common vector for passing disease along. To control for
this & provide a safe environment for children:
1. Use nonporous, easily cleaned toys, preferably those that can
get wet. This allows for the use of disinfectant sprays or
wipes.
2. Disinfect daily & routinely, & immediately after known handling
by a child.
3. Wash your hands thoroughly with an antibacterial soap after
touching these toys. It is preferable to wear gloves to pick up
the toys.
4. Replace old, broken, or worn-out toys. Avoid stuffed animals,
small toys, and non-washable items in your office.
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STERILIZATION
Any instruments that contact, blood, ear drainage, mucous,
or cerumen or saliva containing blood or drainage become
CRITICAL and MUST be sterilized prior to reuse.
1. Gross contamination must be cleaned away first.
2. If using heat sterilization in an autoclave, follow instructions.
3. If using cold sterilization with 2% gluteraldehyde or sporox,
you must:
a. prepare the solution in a covered, plastic tray that was
approved for use with them. Wear gloves when handling
the solution (do not use in ultrasonic cleaners).
b. Submerge them at least 10 minutes for high level
disinfection or for the hours as stated on the solution
(usually 10) for sterilization.
c. Remove instruments and rinse with water or wipe with
disinfectant to remove residual solution and allow to air dry.
d. Change solution at least every 28 days or as instructed on
the label. Change sooner if solution is visibly soiled or
viscous.
Warning: If using gluteraldehyde, the fumes may irritate the
eyes and nose and even cause respiratory problems. Try to
use rubber gloves and safety goggles and handle in an area
with good ventilation. Persons who pour or mix the solution
should also consider wearing eye protection. The chemical
should always be stored in a covered tray. Keep the tray (or
container with the unused solution) tightly shut at all times.
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IMMERSION DISINFECTION
An ultrasonic cleaning machine can be utilized to clean and
disinfect noncritical objects and instruments. The items to
be disinfected in this manner include specula, probe tips and
earmolds that appear free of blood, mucous, or significant
cerumen. They will remain in the disinfectant bath as long
as directed on the label. Remember to clean before
disinfecting.
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HANDWASHING
Handwashing is the single most important activity you can
do to limit the spread of infectious disease.
1. Always wash hands or at least clean with a degermer or
towelette before & after each patient or after handling any
item that may contain blood, drainage, or spittle (such as toys
that young children have handled) if you were not wearing
gloves when such items were touched.
2. Always wash hands before and after eating.
3. Always wash hands before and after adjusting contact lenses
4. Always wash hands after handling waiting room toys.
5. Always wash hands after performing sterilization procedures.
6. Always wash hands after applying cosmetics, lip balm, or
smoking.
7. Always wash hands after removing gloves.
8. Always wash hands after using the washroom.
9. Always wash hands after completing the day’s work.
10. Always wash hands after touching surfaces that patients
might have touch that have not been disinfected.
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The following guidelines apply to washing hands:
1. Remove all rings and put them in a safe place away from
drains. This is because microorganisms cannot be washed
away from the skin beneath the rings and as it is warm and
moist and dark under the rings, growth of microorganisms is
assured. This growth could cause a potential risk to the
patient as well as to yourself.
2. Wash hands before & after each patient. If water is not
available, use a no-rinse antibacterial hand degermer. If soap
& water, use medical-grade antibacterial soap with emollients
to protect hands from drying.
3. First start the water, then apply the liquid antibacterial soap.
Lather the soap, scrubbing your palms, the backs of your hand &
up over the wrists onto the forearms for a minimum of 15
seconds. Clean all surfaces, especially under fingernails and
between fingers.
4. Thoroughly rinse off the soap under running water.
5. Use a paper towel to blot hands dry.
6. Turn the tap off using the paper towel (it may be contaminated
with colonies that rubbed off when you turned the water on
with your hand).
7. Use lotion as needed to keep hands from chapping. Avoid
petroleum-based lotions, as these negatively affect latex
gloves.
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PROPER USE OF GLOVES
1. Select latex (or vinyl if you or your patient shows sensitivity to
latex) examination gloves & make sure that they fit properly
(they should fit like a second skin).
2. Always change gloves between examinations. If a glove
becomes torn or perforated in any way, replace it.
3. Explain that gloves are worn to protect patients & provide the
best in modern care.
4. Place band-aids on open sores or cuts prior to putting on
gloves.
5. Double-glove when treating patients known to be infected with
HIV or hepatitis B.
6. To safely remove the gloves & make sure that the hands do
not make contact with potentially infectious material:
a. Peel off a glove from wrist to finger tip, then grasp in the
gloved hand.
b. Next, using the bare hand, peel off the second glove from
the inside, tucking the first glove inside the second glove as
it is removed.
c. Wash hands thoroughly when completed.
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WASTE MANAGEMENT
If you should find yourself with disposable materials that contain
bodily fluids such as blood, mucous, spittle, or cerumen that may
contain such bodily substances, etc., discard in a manner that
reduces the risk to employees, patients, & the outside
environment. Waste, such as paper towels & gloves, that are
contaminated by significant amounts of blood will be disposed of
in an impermeable plastic bag marked with the international
symbol for biohazard. This waste will be handled by a waste
hauler licensed for carrying medical waste. Most waste can be
placed in the regular garbage. All garbage containers will contain
disposable plastic bags serving as a liner. When placing less
contaminated waste in the regular garbage, attempt to separate
it from the rest of the garbage by sealing it to minimize the
chance of maintenance or cleaning personnel making casual
contact with it. Waste contaminated with cerumen, drainage,
saliva, vomit, etc. will be placed in a sealable plastic bag, then
placed in the regular garbage. Diapers, or material used to clean
up vomit or any bodily substance other than blood, will be
handled likewise. Used disinfectant or sterilizing solution will be
poured down a drain in accordance with label directions.
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