COMMUNICATION AND NOISE - SPEECH-INTELLIG IBILITY OF AIRCRAFT PILOTS WITH AND WITHOUT ELECTRONIC COMPENSATION FOR NOISE

Noise exposure measurements were performed with pilots of the German F ederal Navy during flight situations. The ambient noise levels during regular flight were maintained at levels above a 90 dB A-weighted leve l. This noise intensity requires wearing ear protection to avoid sound -induced hearing loss. To be able to understand radio communication (A TC) in spite of a noisy environment, headphone volume must be raised a bove the noise of the engines. The use of ear plugs in addition to the headsets and flight helmets is only of limited value because personal ear protection affects the intelligibility of ATC. Whereas speech int elligibility of pilots with normal hearing is affected to only a small er degree, pilots with pre-existing high-frequency hearing losses show substantial impairments of speech intelligibility that vary in propor tion to the hearing deficit present. Communication abilities can be re duced drastically, which in turn can affect air traffic security. The development of active noise compensation devices (ANC) that make use o f the ,,anti-noise'' principle may be a solution to this dilemma. To e valuate the effectiveness of an ANC-system and its influence on speech intelligibility, speech audiometry was performed with a German standa rdized test during simulated flight conditions with helicopter pilots. Results demonstrate the helpful effect on speech understanding especi ally for pilots with noise-induced hearing losses. This may help to av oid preretinement professional disability.