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FDA Magazine Offers Sound Advice on Age-Related
Hearing Loss
 May 23, 2005 – One-third of those between the ages
of 65 and 75 has hearing loss and after age 75 it is about half. Most
age-related hearing loss is irreversible but there are ways to
compensate. The cover story in the Food and
Drug Administration's flagship publication, FDA Consumer
magazine, which was just named the Best National Magazine in the 2004
National Association of Government Communicators Blue Pencil
Competition, explores the causes and options for those with
presbycusis.
Sound Advice
About Age-Related Hearing Loss
By Carol Rados, FDA Consumer Magazine
The popular notion that older people are "hard of
hearing" is often true. Hearing loss occurs gradually in most people as
they age. According to the National Institute on Deafness and Other
Communication Disorders (NIDCD), part of the National Institutes of
Health, about 1 out of every 3 U.S. adults between the ages of 65 and 75
has a hearing loss. The NIDCD further estimates that about half of
people 75 and older have some degree of hearing loss.
"We are born with a set of sensory cells, and at
about age 18 we slowly start to lose them," says Hinrich Staecker, M.D.,
Ph.D., director of the otology and neurotology program at the University
of Maryland Medical Center in Baltimore. But because age-related hearing
loss, called presbycusis, progresses so slowly, most people don't notice
any changes until well after age 50.
There are exceptions. Nancy McKinney was in her 40s
when she was diagnosed with mild, age-related hearing loss. Now 51, the
college English professor from Taylorville, Ill., remembers that she
kept telling her students in her classes to speak up. She also recalls
constantly turning up the volume on her TV. Hounded by family and
friends, McKinney eventually sought the advice of one type of hearing
specialist--an otolaryngologist.
"My family was driving me nuts," she says. "But the
main thing was I knew that I couldn't hear." Because her hearing loss
was mild, she was told that she did not need a hearing aid at that time.
Presbycusis, which the NIDCD says usually affects
both ears equally, is most commonly caused by gradual changes in the
inner ear. As people age, structures of the ear can become less
responsive to sound waves, contributing to hearing loss. Staecker says
that early, undetected hearing problems can compound hearing loss
brought on naturally by aging.
Hearing problems can make it difficult for older
people to hear doorbells, car horns, and alarms. Hearing loss also can
make it hard to understand and follow a doctor's advice or respond to
warnings. Its effect on speech communication can reduce a person's
physical, functional, emotional, and social well-being. Isolation and
depression often accompany hearing loss. All of this can be frustrating,
embarrassing, and even dangerous.
Without being aware of it, people with presbycusis
may make small adjustments over time, for example, standing closer to
someone who is speaking or turning up the TV volume, that allow them to
perceive the sounds and cues they otherwise would miss. At some point,
though, the loss may become so severe that these adjustments become
ineffective.
The good news is that there are ways to compensate
for age-related hearing loss. There are devices to help people hear and
communicate more easily, including hearing aids and assistive listening
and alerting devices, such as telephone amplifiers. If you have trouble
hearing, visit your doctor or hearing health care professional to find
out if you have a hearing loss and, if so, how to treat it.
The Food and Drug Administration regulates hearing
aids and other devices used to prevent, diagnose, and treat hearing loss
to ensure that they are safe and effective. But the agency also hopes
people will help themselves by protecting and caring for their ears.
From
Sound Waves to Brain Waves
To better understand hearing loss, it helps to know
how people hear the sounds around them. According to the NIDCD, people
don't just hear through their ears--they hear with their brains. A
vibration, which can be transformed into the sound of a moderate rain, a
rock lyric, or the blast of a chainsaw, is first picked up by the ears
and then "read" by the brain.
The ear is made up of three parts: the outer ear (pinna
or auricle), the middle ear, which includes the eardrum (tympanic
membrane), and the inner ear (cochlea), which is shaped like a snail
shell and lined with tiny hairs.
Hearing loss occurs when the tiny hairs inside the
cochlea are damaged or die, a common occurrence as people age. Hair
cells, which pick up sound waves and transform them into nerve impulses,
do not regenerate. That's why most hearing loss is irreversible.
Sound enters the outer ear and strikes the eardrum,
causing it to vibrate. The eardrum's vibrations are amplified through
the chamber of the middle ear along three tiny interconnected bones,
named for their shapes--hammer (malleus), anvil (incus), and stirrup
(stapes)--which pass on the vibrations of sound waves to the cochlea.
The brain interprets the nerve impulses from the
cochlea as the ring of a doorbell or telephone, words being spoken, or
the honk of a car horn. The combination of pitches, or frequencies, give
different sounds their distinctive qualities. The brain also uses the
source and direction of the sound and loudness as clues to decipher
messages.
Causes and
Symptoms
People lose their hearing when they age because of
gradual changes in their entire auditory system. Sometimes the loss
occurs due to complex changes along the nerve pathways to the brain.
According to NIDCD, presbycusis is usually caused by disorders of the
inner ear or auditory nerve (sensorineural disorders). Sensorineural
hearing loss also can occur as a result of hereditary factors, various
health conditions, and the side effects of some medicines, such as
aspirin and certain antibiotics. Repeated exposure to noise and loud
music is another cause of sensorineural hearing loss.
Presbycusis also may be caused by changes in the
blood supply to the ear because of heart disease, high blood pressure,
blood vessel conditions caused by diabetes, or other circulatory
problems. The loss may be mild, moderate, or severe.
Sometimes hearing loss is a conductive hearing
disorder, meaning the loss of sound sensitivity is caused by
abnormalities of the outer ear, middle ear, or both. Such abnormalities
may include reduced function of either the eardrum or the three tiny
bones that carry sound waves from the eardrum to the inner ear.
Sounds often seem less clear and lower in volume
for a person with presbycusis. The most common symptoms include sounds
of mumbled or slurred speech by others; difficulty in distinguishing
high-pitched sounds; difficulty in understanding conversations,
particularly when there is background noise; hearing men's voices more
easily than women's; and increased sensitivity to loud noises. Tinnitus,
a ringing, roaring, hissing, or other sound, may occur in one or both
ears.
Age-related hearing loss first affects the ability
to hear the highest pitches and only later affects lower pitches. Loss
of the ability to hear high-pitched sounds such as "s" and "th" often
makes it more difficult to tell them apart. Understanding the consonant
sounds in speech is dependent upon our ability to hear high pitches,
says James K. Kane, Ph.D., an audiologist and scientific reviewer in the
FDA's Office of Device Evaluation. "If one cannot hear the high-pitched
sounds, speech becomes less intelligible."
But most important, the symptoms of presbycusis may
resemble other conditions or medical problems, so it's important to
consult a physician for a diagnosis. Even though McKinney's first visit
to the otolaryngologist failed to reveal anything more than minor
age-related hearing loss, she says, "I still couldn't hear." Nearly a
year later, and without a medical evaluation, McKinney mail-ordered
three different types of hearing aids in an attempt to find something
that would help her hear better.
But none fit. "There wasn't one that was
comfortable," McKinney says. She returned all of them for a refund.
Treatment
Since there is no way to reverse age-related
hearing loss, treatment is focused on functional
improvement--compensating for the loss as much as possible. Hearing aids
are the mainstay of treatment, but these devices don't restore hearing
to normal. People can, however, reasonably expect a hearing aid to
improve their ability to communicate.
McKinney says the manufacturer of one of the
hearing aids she tried advised her to consult a second hearing
specialist--an audiologist, who discovered that both of her ear canals
had collapsed.
"Collapsed ear canals are not that uncommon," says
Kane. "But the first step in buying a hearing aid is making sure your
problem is diagnosed properly, since hearing loss may be a symptom of a
more serious medical condition." Kane explains that health care
providers overcome the problem of a collapsed ear canal when taking an
impression for a hearing aid by gently pulling up and back on the outer
ear to straighten the canal before injecting the impression material.
This, he says, is done "to correctly represent the anatomy of the
person's ear, in order to get a proper fit."
Other hearing devices, such as built-in telephone
amplifiers and FM systems that make sounds clearer--with or without a
hearing aid--by delivering sound waves like a radio, also can help
people with age-related hearing loss communicate. Personal listening
systems help people hear what they want to hear while eliminating or
lowering other noises around them. Some, called auditory training
systems and loop systems, make it easier for people to hear someone in a
crowded room or group setting.
Lip reading, which relies on visual cues to
determine what's being said, is another option, usually used by people
who have profound hearing loss and receive very limited benefit from
hearing aids. People who use this method to help overcome hearing loss
pay close attention to people's mouths when they talk. Special trainers
can help people learn these functions. Even so, Kane says, only about 25
percent of the speech sounds we produce are visible on our lips.
In contrast, Kane says that speech reading
encompasses much more than just watching lip movements. It makes use of
the entire communication environment, such as awareness of talker
location, time of day, person speaking, knowledge of conversation topic,
and body language. Kane adds, "All of these provide cues as to what
words are probable and aid in understanding what is said." Both lip
reading and speech reading, he says, are beneficial adjuncts to hearing
aid use.
Currently, there is significant research being done
on restoration of sensory hair cells. A study done by researchers from
the Howard Hughes Medical Institute in Chevy Chase, Md., and reported in
the Feb. 18, 2005 issue of Science, indicates that deleting a specific
gene permits the proliferation of new hair cells in the cochlea. The
study's authors suggested that there might be a gene that produces a
protein that acts as a permanent "brake" on hair-cell regeneration.
Functional hair cells have also been shown to
regenerate in the inner ear after delivery of a gene that controls hair
cell development using gene therapy, as reported in the March 2005 issue
of Nature Medicine. These experiments, Staecker says, may help develop
specific drugs to repair the damaged inner ear and restore some types of
hearing loss.
Types of
Hearing Devices
Hearing aids are tiny instruments worn in or behind
the ear that amplify sounds in people with either conductive or
sensorineural hearing loss. Some need a hearing aid for only one ear.
Others need one for both. A health care professional will determine
whether you need one or two.
Hearing aids have different electronic
characteristics that are chosen to suit the person's particular type of
hearing loss. For example, people whose hearing loss affects mainly
higher frequencies do not benefit from simple amplification, which
merely makes the mumbled speech they hear sound louder. Hearing aids
that selectively amplify the high frequencies markedly improve speech
recognition. Other hearing aids contain vents in the ear mold--a
specially molded piece of Lucite or vinyl material that fits inside the
device--which facilitate the passage of high-frequency sound waves into
the ear.
Staecker says different hearing losses respond
differently to treatment with hearing aids. He describes people's
hearing as similar to listening to a radio. "Certain hearing losses are
like having the volume knob on the radio turned down. When you increase
the volume on your radio from very low to audible, information is heard
more clearly," he says. "In other losses there is a volume problem and a
reception problem. If the station you are listening to is not tuned in
clearly, no matter how much you increase the volume, the information
coming from the radio will not be clear." These types of hearing losses,
he adds, do not necessarily respond well to hearing aids.
Many hearing aids use digital sound processing with
multiple frequency channels so that the amplification can even more
precisely match the person's hearing loss. But Eric A. Mann, M.D.,
Ph.D., chief of the FDA's Ear, Nose, and Throat Devices Branch, says
that some of these devices may not be suitable for older people, who
might find it difficult to manage the small, often complex components.
People who cannot tolerate loud sounds may need hearing aids with
special electronic circuitry that limits the maximum volume of sound to
a tolerable level.
Here are some of the most common types of
hearing aids and their advantages and disadvantages:
Behind-the-ear: carries sound to the ear through a
custom ear mold. These devices are useful for mild-to-severe hearing
loss. Hearing aids attached to eyeglasses are a type of behind-the-ear
hearing aid.
In-the-ear: custom-made to fit in the outer ear.
These devices are useful for mild to severe hearing loss. No outside
wires are visible because they are inside the device.
In-the-ear-canal: custom-made to fit in the ear
canal. These aids help people with all but the worst hearing loss. There
are no outside wires or tubes, and these devices are almost impossible
to see. This device is relatively inconspicuous but is difficult to use
with telephones.
On-the-body: includes a case with a larger
microphone, amplifier, and battery. These devices are for people with
significant hearing loss. The case can be carried in pockets or attached
to clothing, and is connected by a wire to an ear receiver that is
attached to an ear mold.
People who sell, lease, or rent hearing aids have
certain obligations to their customers. Federal rules require that
people visit a doctor to rule out a medical problem before being fitted
for hearing aids by a licensed hearing aid dispenser. The FDA does allow
people to buy hearing aids without a medical exam--for example, because
of religion or personal beliefs--if they sign a waiver provided by the
hearing health care specialist at the time of the purchase. Dispensers
should not encourage people to waive their right to a medical exam,
however, and must advise them that it is not in their best interest to
do so.
In practice, Mann says that many people waive the
requirement. The result, like for McKinney, is that they are not
properly evaluated and fitted before they buy and use hearing aids.
"Unfortunately, consumers may fail to have diagnosed a medically
treatable cause for their hearing loss--something as simple as a wax
buildup or as serious as a tumor of the hearing nerve," he says.
Hearing aids sold through the mail must also meet
FDA regulations. Kane, who reviews hearing aid devices at the FDA,
advises people to adopt a "buyer beware" posture. He says that it's
important for people to have a medical clearance before buying a hearing
aid through the Internet. "It makes sense. A doctor's referral will help
people find a certified, legitimate hearing aid dispenser that they can
rely on."
Kane also says that "auditory rehabilitation is
more than just purchasing a hearing aid." Appropriate counseling from a
professional is critical for success with amplification. "Purchasing
over the Internet precludes this important rehabilitation component," he
says. The patient's spouse and family members also need to be counseled
about the expected limitations and the benefits, because they are a part
of the person's communication environment.
Prices of hearing aids vary considerably, depending
on the technology. Staecker, who regularly refers people for hearing
aids, says to get a second opinion when comparing the price and features
of hearing aids.
As for mobile phones, laboratory testing of more
than 20 hearing aid models found that those tested were susceptible to
interference from the digital cellular phones that are now used in the
United States. In general, behind-the-ear hearing aids experienced
higher levels of interference than in-the-ear devices. Currently, a
testing standard is being developed that will allow consumers to see
ratings of the "compatibility" of specific combinations of mobile phone
and hearing aid models. People should ask their dispensers for more
information on mobile phone use and the type of hearing aid they are
interested in.
Mann adds that the Federal Communications
Commission has recently required that wireless phone manufacturers and
wireless service carriers must make digital wireless phones compatible
with hearing aids within the next five years.
It may take several weeks or months for a person to
learn to interpret the new sounds from a hearing aid, and there is great
variability in the results. Many hearing aid manufacturers offer trial
rental or purchase option plans--usually up to 30 days--to allow their
customers to judge the product's effectiveness and benefits. Check with
your state health department to find out about the regulations covering
trial periods for hearing aids. Kane says that some states have special
licensing divisions within the larger health department.
People with severe to profound hearing loss who
aren't helped by hearing aids may benefit from a cochlear implant. This
is an electronic hearing device that is surgically implanted behind the
ear, with wires and electrodes inserted into the cochlea and a
microphone and transmitter that are worn outside the body. It is
designed to produce useful hearing sensations by electrically simulating
nerves inside the inner ear. Although a cochlear implant can't restore
normal hearing, it can help a person hear sounds and distinguish between
them.
Implantable middle ear hearing devices are designed
to restore some hearing by vibrating the tiny bones of the middle ear in
people with mild to moderately severe sensorineural hearing loss. The
person must have a healthy middle ear, but may opt for an implant simply
because they do not want to use conventional hearing aids. The advantage
of this device over a conventional hearing aid is that it is not
dependent on simply amplifying sound, as is a hearing aid.
Auditory brainstem implants are intended to restore
useful hearing in people who experience total hearing loss when the
removal of tumors damages their cranial hearing nerves. The device
restores the ability to detect certain sounds and speech, although it
does not restore normal hearing. It is surgically implanted into the
brain and electrically stimulates the area that normally receives the
electrical signal from the ear. The patient wears a pocket-sized speech
processor that picks up sound and changes it into electrical pulses that
are transmitted to the implant.
Some Won't Hear
Of It
Doctors know that hearing aids, telephone
amplifiers, and medical evaluations can help individuals with hearing
impairment avoid social isolation and other problems associated with
hearing difficulties. However, Mann says these options are not being
used by the majority of older people who could potentially
benefit--perhaps out of embarrassment, because the hearing loss is
under-diagnosed, or because it is under-treated.
"Some people perceive that there is a social stigma
associated with wearing a hearing aid," he says. Many people who have a
hearing impairment are afraid to admit it, or are unaware of the
sophisticated communication devices available to improve their hearing.
Mann says that many people have unrealistic expectations and are
disappointed in the performance of their device. "Most everyone knows a
relative or an acquaintance who has purchased a hearing aid that now
sits in a dresser drawer," he says.
Mann also cites a significant financial investment
in many cases, and associated with this is the risk of ownership. People
are worried about losing or damaging a high-priced investment, he says.
And there is also some inconvenience on the consumer's part with the
traditional route for obtaining a hearing aid--multiple visits, hearing
aid evaluations, medical evaluations, and follow-up visits to address
specific problems, such as feedback and comfort issues with the ear
molds. "In some cases," Mann says, "there may be trust issues with
hearing aid dispensers based on a history of unethical business
practices with some companies in the past."
But the hearing health care profession agrees that
all of these obstacles can be overcome. Many organizations exist to
provide people with advice and information, and there are professionals
who are willing to work with older people to help them overcome their
fears and concerns.
As for McKinney, she still asks her students to
speak up and sometimes turns up the volume on her TV when it doesn't
inconvenience other family members. But, she says, "How bad does your
hearing have to be before you do something about it?" In her case, it's
no worse than it was initially. "I'm not embarrassed about the fact that
I may need to wear a hearing aid one day," she admits. But the next time
she tries one on for size, she says she'll first have a medical
evaluation and then be referred to a reputable hearing aid dispenser for
a proper fit.
How to Lessen the
Severity of Age-Related Hearing Loss
> Get regular hearing tests
> Limit the amount of noise that
enters the ear
> Maintain normal volume for music and
other forms of entertainment
> Protect your hearing by wearing
earplugs in noisy environments, such as when mowing the lawn or using
power equipment
Hearing Health Care Professionals At a Glance
> Otolaryngologists (M.D. or D.O.) are
licensed physicians who specialize in diseases of the ear, nose, and
throat (ENT), and are medically trained to identify the symptoms of
deafness in context with a person's overall health. They are qualified
by special training to diagnose and treat hearing loss and related
structures of the head and neck. They are commonly referred to as ENT
physicians.
> Otologists (M.D. or D.O.) and
Neurotologists (M.D. or D.O.) are highly specialized otolaryngologists
knowledgeable in the basic sciences of hearing, balance, nerve function,
infectious disease, and anatomy of the head and neck. They also may
manage diseases and disorders of the cranial nerves and skull base.
> Audiologists are qualified by
training and experience to specialize in evaluating and rehabilitating
people whose communication disorders center around hearing. They must
hold at least a master's degree in audiology from an accredited
university. In some states, audiologists must satisfy specific
requirements to be licensed.
> Hearing aid dispensers are people,
partnerships, corporations, or associations that sell, lease, or rent
hearing aids to the public. Individual dispensers must be high school
graduates who have completed at least six months of training under a
licensed hearing aid dispenser. They must pass both written and
practical state examinations.
Buyer Beware!
Sorting help from hype in any media--television,
print, or the Internet--can pose a problem. So remember, if a claim
sounds too good to be true, it probably is.
Here are some points to remember when considering a
hearing aid:
Hearing aids can be expensive. Know your rights in
a hearing aid purchase--including return policies, and how to choose a
reputable seller--to avoid ending up with a costly device that doesn't
work or one that you might not need.
Hearing aid dispensers are required by federal law
to inform people that it is in their best interest to have a medical
exam by a licensed physician before they make a purchase.
Fitting involves careful testing of hearing loss
and selecting the right aid. A reputable seller will teach you how to
use the device and will be available to service it.
Get a referral from your doctor or from friends who
were happy with the services they received.
Check with your state health department to
determine who is qualified to fit hearing aids. Under Maryland law, for
example, audiologists, hearing aid dispensers, and physicians are
qualified. Some states have special licensing divisions within the
larger health department.
Cell phones and hearing aids may not work very well
together because of electromagnetic interference. Ask your dispenser
which hearing aid models are compatible with your mobile phone.
Maryland Attorney General's
Office; FDA
For More Information
American Academy of Audiology
(800) 222-2336
American Speech-Language Hearing Association
(800) 638-8255
American Academy of Otolaryngology--Head and Neck Surgery
(703) 836-4444
FDA information on cochlear implants
For more of the information in the current issue
of FDA Consumer –
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