Download Chapter 9 – Hearing Impairment

Chapter 9 – Hearing Impairment
1. If “deaf” or “hard of hearing”, the person’s
most significant developmental obstacle is the
acquisition of spoken language.
2. Hearing sensitivity is measured in decibels - dB
(units of relative sound loudness)
- zero decibels (0 dB) is the point at which the
average person with normal hearing can detect
the faintest sound
- if the person needs a sound to be louder than a
normal person (higher number of dB’s) to hear
it, then the person has some degree of hearing
loss
3. Physiological definitions
- deaf: hearing losses of 90 dB or greater across
frequencies
- hard of hearing: hearing losses of less than
90 dB across frequencies
4. Educational definitions
- deaf person has a hearing loss that prevents the
processing of linguistic information through
audition (with or without a hearing aid)
- hard of hearing person, with the use of hearing
aid, has sufficient residual hearing to process
linguistic information through audition
5. Age of onset of hearing loss (impact of language
acquisition)
- congenitally deaf: born deaf
- adventitiously deaf: acquired deafness at some
time after birth
- prelingual deafness: at birth or early in life
prior to development of speech and language
(prior to 18 months of age)
- postlingual deafness: after the development of
speech and language
6. Prevalence – only .14% of the population from
6-17 is identified as deaf or hard of hearing by the
public schools
7. Anatomy & Physiology of the Ear
- The outer ear
-auricle & external auditory canal ending at the
tympanic membrane (eardrum)
-least important parts of the ear for hearing
- The middle ear
-eardrum connects to the ossicles (3 tiny bones)
within the middle ear air-filled space - ossicles
conduct vibrations from the “eardrum” to the
“oval window”
-eustachian tube connects the middle ear airfilled spaced to the throat for air-pressure
equalization
-otitis media: infection of the middle ear
caused by viral or bacterial factors preventing
Eustachian tubes’ normal function of ventilating
and draining the middle ear
-otitis media: the most common reason for
doctor visits of children 6 & under (eustachian
tubes change orientation in older children)
-otitis media could result in temporary (but
sometimes chronic) conductive hearing loss OR
rupture of the tempanic membrane, eardrum
(sometimes resulting in some degree of
conductive loss)
-The inner ear (cochlea & vestibular mechanism)
-cochlea is a snail shaped organ at the bottom
of the inner ear
a. the most important part of the ear for hearing
b. vibration of the oval window causes the fluid in
the cochlea to electrically stimulate the auditory
nerve which sends frequency & loudness
information to the brain (danger of loud sounds)
8. Measurement of Hearing Ability
-school screening tests
a. describe screening procedure
b. screening not as accurate as tests done in
audiologist’s office
-pure-tone audiometry
a. establishes an individual’s threshold of hearing at
a variety of frequencies (low to high sounds
measured in hertz-Hz)
b. the threshold for a given frequency is how loud in
decibels (dB) the sound must be to first be
detected
c. described the testing procedure
d. most speech sounds are in the low to high
frequency range of 500-2,000 Hz
-speech audiometry: establishes the dB level (loudness)
at which one can understand speech
9. Causes of Hearing Loss
-conductive hearing loss – interference with the
transfer of sound along the conductive pathway from
outer and middle ear
-sensorineural hearing loss – involves problems in the
inner ear
a. genetic or hereditary factors are the leading cause of
deafness in children
b. acquired sensorineural hearing loss caused primarily
by viral infections & repeated loud sounds –
gunshots, music, machinery
10. English Language &Speech Development
-the most profound effects of a hearing loss are the
comprehension & production of the English language
-poor speech production in deaf children is due to the
lack of auditory feedback
-however, if taught American Sign Language (ASL),
deaf children acquire ASL at the same language
developmental milestones in sign at the same time
as children without a hearing loss do in spoken
language
-current opinion is that ASL is a true language
-however, ASL as a person’s only language limits
his/her access to the larger society
11. Intellectual Ability
-when performance tests, rather than verbal tests, are
administered, there is no difference in IQ between
the deaf & hearing
12. Academic Achievement
-most children with hearing loss have extreme deficits
in academic achievement – particularly READING
-not uncommon for deaf HS graduates to read at no
higher than 4th grade level
-however, highest literacy rates come from deaf
students who have deaf parents who teach them ASL
13. Social Adjustment
-90% of deaf children have hearing parents & many
hearing parents do not learn ASL which results in
lack of easy communication
-loneliness due to isolation in inclusive hearing school
placements
-the value of associating with the deaf culture –
controversy with cochlear implantation
14. Educational Considerations
-historical order of teaching communication skills:
manual - oral - total communication and now bicultural - bilingual
-total communication (in most school settings)
a. utilizes both oral (speaking) and manual
communication (Signing English systems)
b. Speechreading
-teaching hearing impaired to use visual
information to understand what is being said
-very difficult – a large guessing game
-bicultural – bilingual approach
a. ASL is considered the primary language and
English the secondary language
b. Deaf individuals contribute to curriculum &
Incorporate deaf culture
-Accommodations in your classroom
a. your teacher behavior
b. visual support for instruction