to Hearing Loss and Tinnitus
Many pilots and controllers are affected by hearing loss, as is the
general public. Hearing loss may arise from many causes. Some causes are
treatable, while many are permanent and/or progressive. Fortunately for
pilots/controllers, the FAA has very liberal hearing standards for all
classes of certification. For those not meeting standards, waivers or a
Statement of Demonstrated Ability (SODA) are relatively easy to obtain if
the pilot/controller is functional in the aviation environment.
Noise Induced Hearing
The most common cause of occupational hearing loss is caused by repeated
exposures to noise. Over ten million Americans have noise induced hearing
loss and twice that many work in a hazardous noise environment. The
Occupational Health and Safety Administration (OSHA) defines hazardous
noise on a time weighted scale. Chronic exposure to noise above 85
decibels eight hours a day increases the risk of hearing loss. Louder
exposures for shorter periods may have the same effect. Even a single
exposure to a very loud noise may cause some permanent effects. OSHA
mandates that hearing protection be worn in hazardous noise environments
and that employees be trained in the proper use of protective equipment if
the noise can not be eliminated. Monitoring of at-risk employees hearing
is also required.
Noise in Aviation
Most pilots are at least incidentally exposed to loud noises, even if they
fly an aircraft with a very quiet interior. Pre-flighting aircraft on the
tarmac or sitting in aircraft with a cabin door open may cause over
exposure to hazardous noise. The May 4, 1999 issue of USA Today features a
lead article and several others about hearing loss and noise levels in
commercial aircraft. Most aviators have plenty of hours in lighter
aircraft without significant noise protection. Many aviators also have
hobbies or activities that expose them to noise (mowing the lawn,
motorboats, power tools, snow mobiles, etc.) As a general rule of thumb,
if you need to raise your voice to converse at six feet, you are in a
hazardous noise environment.
Protection from noise usually is offered by ear plugs and ear muffs. The
foam ear plugs are very effective in reducing noise. Well fitting ear
muffs also reduce noise. Together, they offer increased protection, but
the effect is not linear. Pilots may preserve their hearing by using
protective devices when on the tarmac or anytime they have to raise their
voice to communicate. Many headsets used in cockpits offer a great deal of
noise reduction passively, such as the David Clark products. Ear pieces
are discrete in appearance but offer almost no protection. For smaller
aircraft with less noise shielding in the cockpit or with engines closer
to the cockpit, the Active Noise Reduction (ANR) headsets may offer a
greater degree of protection that conventional headsets.
Noise Induced Hearing
The anatomy of the ear serves as a very efficient amplification system.
The efficiency of the system is measured by several tests, the most common
being the audiogram. The audiogram measures the hearing threshold in
decibels (dB) at different frequencies measured in Hertz (Hz). When noise
induced hearing loss (NIHL) occurs, the microscopic hair cells in the
cochlea of the ear begin to lose function. The first frequencies to drop
off are near 4000 Hz. Next, the surrounding frequencies of 3000 Hz and
6000 Hz are affected. This change is very subtle. It may manifest as
decreased discrimination, or the ability to understand spoken words
clearly, particularly in a noisy environment.
The classic examples include a man watching TV not being able to hear his
spouse speak behind him or difficulty understanding a higher pitched
womanís voice at a cocktail party with many surrounding conversations and
music. Because background noise in a quiet environment is reduced, many
people with hearing loss may note a background noise or hissing (like
listening to a seashell or soft static), particularly when sleeping. This
is sound perception is called tinnitus. These changes are frequently
permanent and may be progressive if hearing is not protected.
Fortunately for pilots, as their noise exposure increases with their hours
of flight time, they become more skilled and familiar with radio
communications and subtle aircraft sounds. Although their hearing may not
be as acute as younger pilots, their knowledge of expected standard radio
transmissions allows them to function very well in the cockpit. This is
one basis for a FAA SODA for those with marked hearing loss.
Another cause of hearing loss is otosclerosis. Otosclerosis involves a
stiffening of the eardrum (tympanic membrane) and the three tiny bones
responsible for amplifying sound pressure waves, the "hammer, anvil and
stirrup." This usually occurs as individuals age and may have a familial
predilection. Hearing aids may improve hearing in both otosclerosis and
Hearing Aids in Pilots
Note that a pilot/controller may take an FAA PE while using a hearing aid.
If they take a hearing test with a hearing aid in place, the medical
certificate usually will bear the restriction "Must use hearing
amplification." This means the pilot/controller has the option of using a
hearing aid while flying or controlling, using a headset, using an
earpiece or an overhead speaker system.
However, there are differences between airmen and controller standards.
The concern for controllers is that an ear piece is in one ear and the
other ear is used for communications within the tower cab. For this
reason, the FAA will not allow unilateral deafness in controllers. There
are some regional variations in this policy. If a controller doesn't meet
audiogram standards, then they are required to pass with 70% for speech
discrimination. They also require supervisory statements and then can be
given Special Consideration for controlling.
Colds, Ear Blocks and Hearing
Colds and ear blocks decrease the ability of the ear drum to move fully
with sound pressure waves. This temporarily reduces hearing. Hearing
should return to normal when the condition is improved. Decongestants will
also improve the hearing. Be cautious of trying to fly with decongestants
to "clear the ears." Although this practice may allow a pilot to take off
safely, problems are frequently encountered as ambient pressure rises on
descent. The risk is an ear block, with possible vertigo or a ruptured ear
drum. Both are very unpleasant and potentially compromise flight safety. A
pilot may consider having a bottle of Afrin or neosynephrine nasal spray
as an emergency "get me down" treatment but should never fly if this
medication is required to clear ears prior to flight.
Other Causes of Hearing Loss
Less common causes of hearing loss may be more profound in one ear and may
indicate the need for thorough medical evaluation. Two of these conditions
have serious implications for a controller or pilotís medical certificate,
but evaluation should not be delayed for fear of "having the medical
The first condition is an acoustic neuroma. This is a tumor of the eighth
cranial nerve that provides hearing and balance inputs to the brain from
each ear. This type of tumor is usually slow growing but must be removed.
It is detected by a CT or MRI scan, although sometimes may be seen by
looking directly in the ear. Surgery is usually curative although hearing
may be permanently affected and balance temporarily affected depending on
the amount of nerve preserved at surgery. Again, FAA hearing standards
allow the use of BOTH ears to pass, not just EACH ear. A pilot/controller
could be completely deaf in one ear and still meet FAA standards. This may
present problems in the cockpit using an earpiece in one ear for radio
communications and spoken voice for crew cockpit communications.
The other serious cause of hearing loss for aviators is Meniereís
syndrome, sometimes known as endolymphatic hydrops. Classically this
usually presents as a triad of sudden unilateral hearing loss, roaring
tinnitus and episodic vertigo. Not all three components are required for
this diagnosis. Obviously, the sudden, unpredictable vertigo associated
with this syndrome presents a safety risk to a pilot/controller. The
condition is disqualifying for all classes of certification.
Some treatments may allow recertification after the condition is resolved.
One treatment involves the use of salt restriction and diuretics (fluid
pills) since one theory about the cause involves excess fluid in the
components of the inner ear. Another treatment is the surgical
construction of a shunt to remove fluid from the inner ear. Surgery should
be done at an medical center experienced in this condition. Both
treatments have variable results. For favorable review of a medical
application in a pilot/controller with a history of this condition, they
must be free of vertigo for an extended observation period. Provocative
testing of balance (posturography) and vertigo using an ENG (electronystygmogram)
may be required. The FAA will require periodic reports from the monitoring
physician of an individual with a history of Meniereís syndrome.
FAA Hearing Standards
The current FAA hearing standards for all classes of certificate (FAR
67.105, .205, .305) require an airman to hear the SPOKEN voice at six feet
using BOTH ears with the pilot's back turned to the examiner. Previously
the standard was the WHISPERED voice using EACH ear at 20 feet, six feet
and three feet for First, Second and Third Class certification,
respectively. For those airman who can not pass this test, two other tests
are authorized. One is a speech discrimination score of 70%. The other is
audiometry (hearing using pure tones in a headset) as below:
Frequency (Hz) 500 1000 2000 3000
Better ear (dB) 35 30 30 40
Poorer ear (dB) 35 50 50 60
For controllers from Order 3930-3a:
Frequency (Hz) 500 1000 2000 4000
Better ear (dB) 25 25 25 50
Poorer ear (dB) 30 30 30 50
The best solution to preserving hearing is to protect yourself from
hazardous noise. If you do experience a hearing loss, get it evaluated by
experts. Rest assured that the FAA will generally certify or waive most
pilots/controllers with significant degrees of hearing loss, assuming the
condition is stable and not associated with ongoing vertigo.