[Hearing loss in airplane crew]

From 1970 through 1984, 289 airplane crew who failed to satisfy criteria for physical examination for airplane crew were studied. The hearing loss in left ear was more frequently found than in the right. Because noise level (Leq) in cockpit was found to be about 90 dB, the noise did not seem to have caused the hearing loss. The authors presumed that hearing loss in cockpit crew might be either due to head phone sound from which the aircrew hear ATC (Air Traffic Control) from the control tower or to an individual hypersusceptibility.