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Hearing Aids – Combined Review
URLEND 2011
Nancy Hohler
Jeanne Raney
Natalie Allen
Background
Hearing aids enable many children with impaired hearing to hear better and, for many, well enough to
develop normal speech, language, social communication, and learning skills. Determining whether
hearing aids will be helpful for a child depends upon the type, severity and configuration of the hearing
loss, family involvement, and follow-up interventions, including speech and language therapy. For
children with hearing impairment, the primary aim of hearing aid use is to enable them to hear and
understand sufficiently to develop their own speech and language. Hearing aids vary in their ideal
application, technology, size, cost, durability, and potential complications. If chosen and used
appropriately, hearing aids can be effective in allowing normal development in the face of hearing
impairment.
Assessment and Evaluation
Evaluation of pediatric patients should be performed by a pediatric audiologist, trained and experienced
in assessing children. After hearing loss is confirmed, the pediatric audiologist will refer the child to an
otolaryngologist for further assessment. Together the otolaryngologist and the audiologist will
collaborate with the family to determine rehabilitation. To find a pediatric audiologist, families and
pediatricians can contact one of two professional organizations that audiologists belong to: the
American Academy of Audiology www.audiology.org or the American Speech, Hearing and Language
Association www.asha.org.
Types of Hearing Loss
Hearing loss can be categorized by the part of the auditory system that is impaired and the severity of
the impairment. There are three basic types of hearing loss: conductive hearing loss, sensorineural
hearing loss, and mixed hearing loss.
Conductive hearing loss occurs when sound is not conducted efficiently through the outer ear canal to
the eardrum and the tiny bones (ossicles) of the middle ear. Conductive hearing loss results in inability
to hear faint sounds. Some causes of conductive loss can be corrected medically or surgically. For
example, middle ear fluid or Eustachian tube dysfunction may be resolved with treatment of infection or
placement of ventilating tubes. In some cases, absence of an outer ear or ear canal may be surgically
repairable, but will likely require hearing aids for some time. Absence of the middle ear usually requires
permanent use of hearing aids. In general, traditional hearing aids work well for conductive hearing
loss. In some cases a surgically implanted or osseointegrated hearing aid is preferred.
Sensorineural hearing loss (SNHL) results from damage to the inner ear (cochlea) or to the nerve
pathways from the inner ear to the brain. It is the most common type of hearing loss and usually cannot
be medically or surgically corrected. SNHL reduces the ability to hear faint sounds; speech that is loud
enough to hear may sound muffled or unclear.
Causes of SNHL in children include:
● Illnesses, including CMV, bacterial meningitis
● Drugs that are toxic to hearing
● Hearing loss that runs in the family (genetic or hereditary)
● Head trauma
● Malformation of the inner ear
● Exposure to loud noise
● Eighth nerve lesions
● Prematurity
Most traditional hearing aids are designed for SNHL.
Mixed hearing loss describes a condition where a conductive hearing loss occurs in combination with
a sensorineural hearing loss (SNHL). Examples in children occur when a child has SNHL and also
experiences conductive loss because of otitis media, causing hearing to be poorer than it was from the
SNHL alone. Traditional hearing aids can be used with mixed hearing losses.
The degree or severity of hearing loss is described by the threshold of loudness at which sound can be
heard, in ranges of decibels – mild hearing loss (26 to 40 dB HL), moderate hearing loss (45 to 60 dBHL),
severe hearing loss (65 to 85 dB HL), and profound hearing loss (91+ dB HL).
The configuration or shape of a hearing loss refers to its degree and pattern across frequencies (tones),
as illustrated in a graph called an audiogram. For example, the configuration of a hearing loss might
show good hearing in the low tones and poor hearing in the high tones. Some hearing loss
configurations are flat, indicating the same amount of hearing loss for low and high tones.
The degree and configuration of hearing loss are factors the audiologist considers when selecting and
recommending hearing aids.
Other descriptors associated with hearing loss are:
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Bilateral versus unilateral.
Symmetrical versus asymmetrical, depending on whether the degree and configuration of
hearing loss are the same in each ear.
Progressive versus sudden hearing loss – progressive means that hearing loss becomes worse
over time. Sudden means hearing loss that happens quickly, which should prompt immediate
medical attention to determine its cause and treatment.
Fluctuating versus stable hearing loss.
A progressive or sudden hearing loss will require a hearing aid that is capable of providing more
amplification as the hearing loss becomes worse. The best hearing aid for a fluctuating hearing loss will
provide different levels of amplification to accommodate the fluctuation.
Styles of Hearing Aids
The type, degree and configuration of hearing loss will determine which style of hearing aid may work
best for the child, with smaller models generally suited for less significant losses and larger styles suited
for any degree of hearing loss, including severe and profound.
Behind-the-ear (BTE) aids: All parts of the aid are contained in a small plastic case that rests behind the
ear and is connected to an earmold by a piece of clear tubing. The behind-the-ear (BTE) hearing aid is
the type most commonly recommended for infants and young children for a number of reasons,
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It accommodates various earmold types.
The earmold detaches and can be easily remade as the child grows.
The earmold is easy to handle clean.
Parents and caregivers can easily do a listening check and make adjustments.
It accommodates a wide variety of hearing losses.
It can be made with direct audio input or a telecoil, so it can be used with other listening
devices.
The earmolds are made of a soft material that is safer and more comfortable for tiny ears.
Behind-the-ear aid: open fitting: A small plastic case rests behind the ear, and a very fine clear tube
runs into the ear canal. Inside the ear canal, a small, soft silicone dome or a molded, highly vented
acrylic tip holds the tube in place. These aids offer cosmetic and listening advantages and are typically
used for adults and some older children as well.
In-the-ear (ITE) aids, In-the-canal (ITC) and completely-in-the-canal (CIC) aids: All parts of the aid are
contained in a shell that fills in the outer part of the ear (as shown) or are partly or completely fit into
the ear canal (CIC). They are the smallest aids available and offer some cosmetic and listening
advantages. These are most often not appropriate for children as their ears are too small or growing
rapidly, requiring frequent changes in size.
There are also special hearing aids built to handle very specific types of hearing loss or circumstances:
CROS hearing aids route sounds coming to one ear over to the other ear. These devices are for use by
individuals who have no hearing in one ear. In special cases, hearing aids can be built into eye glasses for
individuals who need that type of fitting.
Eyeglass Aids Hearing aids and glasses were combined in the 1950s but are no longer seen as viable
options in most cases.
Disposable Hearing Aids have a non-replaceable battery. These aids are designed to use power
sparingly, so that the battery lasts longer than those used in traditional hearing aids. Disposable hearing
aids aim to minimize maintenance (battery replacement, aid adjustment, and cleaning). To date, two
brands of disposable hearing aids are available. Both are digital, but they are used in very different ways.
One is a BTE hearing aid that is bought online and worn like any other BTE device. When it runs out, the
user replaces it with a new one. The other requires a professional to implant it deep in the ear canal and
to remove and replace it when the battery runs out. Disposable hearing aids are not recommended with
children.
Bone conduction hearing aids use a headband and a bone vibrator for individuals who have no ear canal
or outer ear. These devices bypass the outer and middle ear and directly stimulate the cochlea or inner
ear. This is often the only alternative for children born with a permanent conductive hearing loss, such
as atresia of the ear canal, or chronic draining otitis media that precludes fitting a hearing aid.
A relatively new innovation is the osseointegrated hearing aid (bone anchored), which is implanted in
the skull. This device has three parts: a titanium implant, an external abutment, and a detachable sound
processor. Currently the FDA approves bone anchored devices for children age 5 and older.
Middle ear implants are hearing systems implanted in the space behind the eardrum that mechanically
vibrate the middle ear structures. This device has two parts: an external portion and an implanted
portion. Middle ear implants are used when a conductive hearing loss results from permanent damage
to or the absence of the ossicles.
A cochlear implant provides direct electrical stimulation to the auditory (hearing) nerve in the inner ear.
Children and adults with a severe to profound sensorineural hearing loss who cannot be helped with
hearing aids may be helped with cochlear implants. The cochlear implant does not result in “restored”
or “cured” hearing. It does, however, allow for the perception of the sensation of sound. Children as
young as 6 - 9 months of age have received cochlear implants, and the potential exists for successful
implantation at younger ages
It is generally agreed that the best child candidates for cochlear implant are those who:
● Have profound hearing loss in both ears
● Have had limited benefit from hearing aids
● Are healthy and have no medical conditions that would make the surgery risky
● Are involved (when able), along with their parents, in all the steps in the process
● Understand (when able), along with their parents, their role in the successful use of cochlear
implants
● Have (when able), along with their parents, realistic expectations for cochlear implant use
● Are willing to be actively involved in their habilitation/rehabilitation
● Have support from their educational program to emphasize the development of auditory skills
Components of a Hearing Aid
 Batteries
o Zinc air cell batteries are used in virtually all current-day hearing instruments. They are
activated by removal of a tab which allows air to enter the battery and they have
excellent shelf life when stored properly (approx. 2-3 years). These replaced mercury
and silver oxide batteries. They are available in all sizes (675 to 5A) and high-power.
Cost is ~ $1.00 per battery
o All hearing aid batteries are toxic. Keep them stored in a safe place away from
children and pets. A swallowed battery is a medical emergency and the individual
needs medical attention immediately.
 Microphone (s)
○ Omnidirectional (omni)– have one port of entry for inputs and equal sensitivity to inputs
from all directions; currently, most manufacturers offer an omni-directional microphone
option in all styles including canal styles.
○ Bidirectional- Not used very often
 Receiver – converts electrical energy in to acoustic energy
 Amplifier – amplifies the acoustic signal before it enters the ear canal
Types of Hearing Aid Circuitry
 Analog
○ Representation of sound by electrical current
○ “Older”, more conventional technology
 Digitally Programmable
○ Analog components programmed/adjusted by an external digital source (computer)
 Digital – most current hearing aids
○ Both the audio circuit and the additional control circuits are fully digital.
○ Hearing aid programmed with an external computer temporarily connected to the
device. Fully digital hearing aids can be programmed with multiple programs that can
be invoked by the wearer, or that operate automatically and adaptively. These programs
reduce acoustic feedback (whistling), reduce background noise, detect and
automatically accommodate different listening environments (loud vs soft, speech vs
music, quiet vs noisy, etc.), control additional components such as multiple microphones
to improve spatial hearing, transpose frequencies (shift high frequencies that a wearer
may not hear to lower frequency regions where hearing may be better), and implement
many other features. These programs can be determined on an individual basis for each
patient.
Cleaning Your Hearing Aid
Keeping your hearing aids in good working order prevents many future problems. To clean your aid you
will need a wax pick, brush, and hearing aid blower. If not included with your hearing aid, they can be
purchased from an audiologist or vendor.
After removing the hearing aid from your ear, remove any wax from the ear mold or tubing with the
hearing aid pick and wipe the exterior of the aid and mold with a soft cloth. These should be done daily.
Clean the battery compartment by removing the battery and gently brushing interior. Replace battery
and close the casement.
Earmolds can be removed from the aid by first locating the end of the tube where it connects with the
ear hook; then twist and pull gently. Using warm water and mild soap, wash the earmold, then rinse
with clean water. Place the blower on the end of the tube and squeeze. This should force water out of
the tube. Allow to dry overnight before reconnecting to ear hook.
Moisture
Moisture is a major cause of hearing aid failure, resulting in circuitry problems and distortion. Moisture
gets into the hearing aid primarily through condensation from the warm moist environment of the inner
ear. If possible, avoid wearing your hearing aid in wet, humid or steamy conditions or during strenuous
exercise.
If moisture droplets are seen in hearing aid tubing, disconnect the tubing gently from ear hook and, with
a hearing aid blower, blow air through the tubing to force out moisture and then allow it to dry
overnight. With in-the-ear models, the only way to combat moisture is to remove them and allow them
to dry out.
Never put your aids in a conventional or microwave oven to dry or leave them in direct sunlight.
Excessive heat may melt plastic components and microwaves will destroy all of the electronic
components.
Special moisture-dispersing tubing or “Dry Aid” kits are available and may be worth trying if moisture
problems recur.
Hearing Aid Checks
Hearing aid checks should be performed daily. Parents or teachers can perform checks for young
children; school-age children should be taught to perform checks and, when competent, perform them
independently.
First, check the exterior of aid for any cracks, holes or tears. Remove the battery and test with a hearing
aid tester. After reinserting or replacing battery, close the compartment completely. Turn the O-T-M
switch to “off” (O) position. Turn the volume to the lowest setting and turn the switch to the
“microphone” (M) position. Put one end of a hearing aid stethoscope into the ears of hearing person
and say several vowel and consonant sounds. None should be distorted. Once the hearing aid has been
checked and verified to be working properly, place it in the ear and listen for feedback. If feedback is
present, remove the aid. Cover the opening of the canal in earmold with thumb. If you still hear
feedback, there is a problem with the aid. If not, it means the earmold was not fitted tightly, which
could be a sign of a bad fit.
Ear wax is the normal way that the ear protects the ear canal and ear drum (tympanic membrane). Most
peoples’ ear canals clear wax without help. A hearing aid can impede this process resulting in wax buildup behind the earmold, which can damage a hearing aid. It can also cause hearing aid feedback—an
extremely high-pitched whistling sound—and reduce hearing effectiveness by blocking sound.
No one should try to remove ear wax themselves. Using a swab or any object in the ear canal can push
the wax back further and cause it to become impacted, which can cause pain and further hearing loss.
Current guidelines from the American Academy of Otolaryngology—Head and Neck Surgery Foundation
recommend that individuals with hearing aids have their ears cleaned professionally twice a year.
Funding & Costs
Cost and Life of Hearing Aids
The cost of a single hearing aid can vary from $500 to $6,000 or more, depending on the level of
technology and whether fitting fees are included. Most private US health care providers do not provide
coverage for hearing aids for adults, but some, including many Medicaid programs, cover hearing aids
for children. Less expensive hearing aids can be found on the internet or in mail order catalogs but some
of these use poorly made sound amplifiers and are not recommended. The cost of hearing aids is a taxdeductible medical expense for those who itemize medical deductions.
Children should be evaluated for hearing aids by a pediatric audiologist who can monitor the child’s
response to the hearing aids and insure that they fit appropriately. In many states, before a hearing aid
can be fit on a child, an otolaryngologist must provide medical clearance in the form of a prescription.
This is to ensure that treatable causes of hearing loss have been assessed.
The life of a hearing aid depends on many factors, including care. In many cases a hearing aid can last
up to five years or longer. Some insurances will not authorize hearing aids more than once every five
years unless the hearing loss has changed significantly and the current aids are no longer appropriate.
Many pediatric providers recommend hearing aids from companies that are pediatric-friendly and offer
extended warranties for loss and damage. There are also private insurance companies that offer
insurance plans that cover loss and damage of hearing aids and other assistive devices for a fee.
Funding Sources
Hearing Aid Recycling Program (HARP) http://health.utah.gov/cshcn/hsvs/harp.htm
This program obtains previously owned hearing aids and makes them available to hearing
impaired children throughout Utah. The program does not pay for outside testing or fitting
services.
HIKE Fund Inc. http://www.thehikefund.org/
Hearing Impaired Kids Endowment Fund, supported by Job’s Daughters International, provides
hearing devices for about 100 children a year who have hearing loss and whose parents are
unable to meet this special need financially.
AUDIENT Alliance for Accessible Hearing Care http://www.audientalliance.org/
The AUDIENT Alliance for Accessible Hearing Care Program is designed for individuals whose
income is above the government's established poverty levels, but still find it difficult to afford
quality hearing care.
The Hear Now Program http://www.deafchildren.org/links.aspx
The Hear Now Program of the Starkey Hearing Foundation is a national program providing
assistance, to those permanently living in the US, to acquire hearing aids through an application
process. All applicants must meet the program's financial criteria. Hear Now works with licensed
practitioners in the applicant's area.
Miracle Ear Children’s Foundation http://www.miracle-ear.com/childrenrequest.aspx
Miracle-Ear Children's Foundation provides free hearing aids and services to children from lowincome families.
Listen Up http://www.listen-up.org/haidfund.htm
Sources of hearing aid and cochlear implant funding.
Oticon Pediatrics http://www.oticonusa.com/
Oticon Pediatrics offers a loaner bank program. The program will provide hearing aids for
children, birth to three, who are in need of immediate amplification when amplification is not
otherwise readily available.
Other Resources
American Society for Deaf Children www.deafchildren.org/links.aspx
ASCD, founded in 1967, is a national, non-profit organization whose web site offers information
and resources for children with hearing impairment and their families.
Services
Sound Beginnings at Utah State University http://www.soundbeginnings.usu.edu/
An early education program that provides home- and center-based services to children with
hearing loss whose families want their children to learn to listen and talk.
Parent Infant Program (PIP) http://www.usdb.org/pip/default.aspx
Recognizing that early identification and services for children with sensory loss can significantly
improve developmental potential, PIP provides hearing and vision services to children, under
the age of three who have vision or hearing impairments, and their families. Services are
offered throughout Utah. The PIP program works in collaboration with Utah’s Baby Watch Early
Intervention system.
Utah’s Baby Watch Early Intervention Program
http://www.utahbabywatch.org/eiservices/index.htm
Provides early identification and developmental services for families of infants and toddlers,
ages birth to three.