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Hearing in military pilots: one-time audiometry in pilots of fighters, transports, and helicopters.

INTRODUCTION
Pilots are exposed to potentially harmful levels of noise, the actual consequences of which are still poorly documented. We have determined the audiometric profiles of pilots as a function of age and type of aircraft (i.e., fighter, transport, helicopter) and have searched for risk factors of deafness other than noise in a pilot population.


METHODS
We examined 521 French military pilots ages 20-40 yr during their annual medical check-ups. Pilots were interviewed using a standardized questionnaire and data from tonal audiograms of both ears were collected. Hearing levels were compared between groups of age and aircraft category.


RESULTS
Abnormal hearing levels in pilots were found essentially at high frequencies with a marked notch on audiograms at 6 kHz. Left ears had a significantly poorer performance compared with right ears. At a given age, transport pilots had, on average, better hearing at 8 kHz than other pilots, despite a higher number of flying hours. In addition to the 6 kHz notch, helicopter pilots showed a significant hearing loss at 3 kHz. Such an enlargement of the impaired frequency range can disturb speech communication. Prevalence of otitis media in childhood was significantly higher in pilots with abnormal hearing.


DISCUSSION
Pilots flying fighter and helicopter aircraft are at a higher risk of hearing loss compared with pilots flying transport aircraft. Improvements in ear protection seem particularly needed for the left ear. Hearing losses can potentially compromise speech communication in helicopter pilots.