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aircraft of the type for which the applicant’s licence and ratings are valid may be
used.
Class 2 Medical Assessment:
6.4.4 Hearing requirements
Note.— Attention is called to 2.7.1.3.1 on requirements for the issue of instrument
rating to applicants who hold a private pilot licence.
6.4.4.1 Applicants who are unable to hear an average conversational voice in a quiet
room, using both ears, at a distance of 2 m from the examiner and with the back
turned to the examiner, shall be assessed as unfit.
6.4.4.2 When tested by pure-tone audiometry, an applicant with a hearing loss, in either
ear separately, of more than 35 dB at any of the frequencies 500, 1 000 or 2 000
Hz, or more than 50 dB at 3 000 Hz, shall be assessed as unfit.
6.4.4.3 Recommendation.— An applicant who does not meet the requirements in
6.4.4.1 or 6.4.4.2 should undergo further testing in accordance with 6.3.4.1.1.
Class 3 Medical Assessment:
6.5.4 Hearing requirements
6.5.4.1 The applicant, when tested on a pure-tone audiometer, shall not have a hearing
loss, in either ear separately, of more than 35 dB at any of the frequencies 500,
1 000 or 2 000 Hz, or more than 50 dB at 3 000 Hz.
6.5.4.1.1 An applicant with a hearing loss greater than the above may be declared fit
provided that the applicant has normal hearing performance against a background
ICAO Preliminary Unedited Version — October 2008 III-12-9
noise that reproduces or simulates that experienced in a typical air traffic control
working environment.
Note 1.— The frequency composition of the background noise is defined only to the
extent that the frequency range 600 to 4 800 Hz (speech frequency range) is
adequately represented.
Note 2.— In the speech material for discrimination testing, both aviation-relevant
phrases and phonetically balanced words are normally used.
6.5.4.1.2 Alternatively, a practical hearing test conducted in an air traffic control
environment representative of the one for which the applicant’s licence and
ratings are valid may be used.
Before discussing hearing to any extent, it is necessary to have a basic knowledge of sound. The frequency of
a sound wave determines pitch and is expressed in cycles per second or hertz (Hz). The wave form of a pure
tone is sinusoidal. The amplitude of the sine wave determines its intensity.
The weakest sound pressure, p, detected by an average young person with undamaged hearing in quiet
conditions, the sound perception threshold, is generally reported as the sound pressure level (SPL) of 20 μPa
(micropascals) = 2 × 10−5 Pascal (Pa) at 1000Hz. When considering different sound (noise) levels and their
effect on human hearing, it is more convenient to use a relative unit for sound (noise) intensity measurements,
namely the decibel (dB), which is defined as 20 times the common logarithm of the ratio between two sound
pressure levels:
20 log (p2/p1) dB
ANATOMY AND PHYSIOLOGY
Hearing involves the transmission of sound to the inner ear, the change of the sound wave to a neural impulse,
its transmission to the brain and perception of the impulse by the brain. Every individual has a hearing
threshold in each frequency audible to him. This varies considerably among individuals and changes in the
same individual with age.
In man, the auricle does little to increase the sensitivity of hearing. Its occasional absence in congenital or
traumatic conditions is not associated with an appreciable loss of hearing. Occlusion of the external auditory
meatus affects hearing seriously. Hard impacted cerumen (earwax) is a good example.
When the good ear is turned toward the sound source, monaural hearing is only slightly less acute than
binaural hearing. But, if the head is turned in the opposite direction, hearing may be reduced by as much as 20
dB in some frequencies. A more serious handicap of unilateral deafness is the patient's difficulty in localizing
a sound source.
If the auditory canal of an applicant with normal hearing is occluded tightly by the examiner's finger, the
resultant hearing loss in that ear is generally no greater than 40 dB. This loss still permits the applicant to hear
a low or slightly raised voice. A common mistake in testing hearing is to assume that one ear is adequately
masked by the finger when actually it is not. The applicant then receives credit for better hearing than is
present.
Perforations of the tympanic membrane exert a variable effect on hearing depending upon their size and
location and whether or not there are associated changes in the middle ear. An intact tympanic membrane is
ICAO Preliminary Unedited Version — October 2008 III-12-10
not absolutely essential for normal hearing. Any interference with the ossicular chain, however, is very likely
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Manual of Civil Aviation Medicine 2(76)
