Page 14 - February 2015 Volume 9, Number 2

Wa’did
loss. This is exacerbated by prolonged or very sudden loud noise exposure, ear infections, and genetics, as well as multiple other factors. Pilots have been especially prone to decreased hearing because of the high noise environment of the cockpit. Hopefully, the emergence of high quality ANR headsets over the last 15-20 years will minimize this risk for the new generation of pilots.
H
e Say?
Most pilots intuitively understand that good vision is necessary, but what about hearing? What are the FAA standards, and, if a pilot does not meet them, can one still get a medical certificate?
by Dr. Jerrold Seckler
Of all our sense organs, it could be argued that the ear is the most complex. It consists of three distinct parts, the outer, middle and inner ear.
The outer ear, also called the pinna, is the part of the ear we see sticking out from the sides of our head. It collects sound waves and channels them into a tube, the ear canal, that ends at the boundary of the outer and middle ear called the tympanic membrane, or eardrum. Sounds cause the eardrum to vibrate, and these vibrations are amplified and passed through the middle ear by three small bones that transmit the vibrations to the actual hearing organ, the cochlea, in the inner ear. This organ contains fluid and many cells that have fine “hairs” sticking up from the cell surface. The vibrations transmitted from the middle to the inner ear cause movement of the fluid, which in turn stimulates the tiny hairs on the cochlea cells to generate an electrical current that travels from the inner ear to the hearing center in the brain.
There are other parts of the ear as well, such as the Eustachian tube, which is necessary to balance the pressure between the outer and middle ear (that’s what gets blocked during rapid descents), as well as the semi-circular canals which play an important role in balance. For now, let’s just concentrate on hearing as it relates to FAA certification.
There are two main types of hearing loss – conductive and sensorineural. Conductive loss results from any condition that impairs the transmission of the sound wave from the pinna to the cochlea. Common causes include plugging of the ear canal by wax, otosclerosis (stiffening of the bones of the middle ear) and infectious processes in the middle ear. Sensorineural hearing loss is due to a problem in the inner ear, most usually deterioration of the hair cells that convert the vibrations of sound into electrical signals that travel to the brain. As we age, all of us experience some degree of hearing
12 • KING AIR MAGAZINE
Interestingly, hearing loss is not a disqualifying condition for any category of medical as long as the amount of loss is not to a degree that makes normal communication impossible. Even then, pilots who are totally deaf may still qualify for a medical certificate.
Unlike visual testing, which is fairly thorough, the test for hearing is quite simple and straightforward. For all classes of medical, all the applicant needs to do is demonstrate the ability to hear a normal spoken voice with his/her back to the examiner from a distance of six feet. What that means is simply that during the exam, the examiner should have you turn your back, and, from a distance of six feet say a few things and then ask you what was said. Unlike with the eyes, the ears are not tested separately. You do this test using both ears. Even if you are totally deaf in one ear, you may pass without difficulty.
If you cannot pass that test, there are other options. For example, you may choose to have audiometric testing. If you do, you must demonstrate the following thresholds:
What this test measures is the softest sound you can reliably hear at different frequencies. A whisper is about 20 dB, and a jet engine is roughly 180 dB. The frequencies, measured in Hertz (Hz), correspond to pitch, with higher pitched sounds having a higher frequency. In this test, both ears are measured and you have to be able to hear a 35 decibel (dB) tone at 500 Hz, a 50 dB tone at 1,000 and 2,000 Hz and a 60 dB tone at 3,000 Hz in your worst ear, and 35, 30 or 40 dB tones at those frequencies in your better ear in order to pass.
If you can’t pass the standard hearing tests, you may be able to meet the standards using a hearing aid. If so, there will be a limitation on your certificate stating it is “Valid only with use of hearing amplification.” Note that it does not require you to use your hearing aid in the cockpit. Any form of amplification, including a headset, will meet the requirement.
Condition
500 Hz
1,000 Hz
2,000 Hz
3,000 Hz
Better Ear
35 dB
30 dB
30 dB
40 dB
Worst Ear
35 dB
50 dB
50 dB
60 dB
FEBRUARY 2015