Accession Number : AD0717394

Title :   Auditory Processing for Speech Intelligibility Improvement,

Corporate Author : CIVIL AEROMEDICAL INST OKLAHOMA CITY OKLA

Personal Author(s) : Tobias,Jerry V.

Report Date : APR 1970

Pagination or Media Count : 12

Abstract : Pilots of light aircraft often seem to prefer loudspeakers to earphones even though covering the ears helps most of them to improve the signal-to-noise ratio of speech transmissions, and to decrease the pilot's exposure to fatiguing noise. The auditory-fatigue problem can be handled by pilot education; the problem of deteriorating signal-to-noise ratios, though, can be approached not just by putting earphones on fliers but also by applying to the loudspeaker situation some of the theoretical principles that have led to techniques of apparent signal-level improvement and real speech-intelligibility improvement under earphones. The human auditory system, appropriately stimulated, is capable of creating the effect of an improved signal-to-noise ratio without actually changing either the signal or the noise intensities. Tests of these techniques show that their proper application to a loudspeaker-listening situation is equivalent to a 5-dB improvement in signal-to-noise ratio. Since the method is based in the human observer's signal-processing ability, it requires no special equipment in the aircraft. Two loudspeakers are used, driven from the same signal source, but with the two speakers wired in opposite phase to each other. Within broad limits, variations in speaker placement permit the improved results. These limits are defined. (Author)

Descriptors :   (*SPEECH, *INTELLIGIBILITY), (*HEARING, SIGNAL-TO-NOISE RATIO), AUDITORY PERCEPTION, AUDITORY SIGNALS, AIRCRAFT NOISE, AVIATION SAFETY

Subject Categories : Anatomy and Physiology
      Non-radio Communications

Distribution Statement : APPROVED FOR PUBLIC RELEASE