Accession Number : AD0659331

Title :   A BEHAVIORAL STUDY OF THE SOUND-SHADOW EFFECT IN IMPULSE NOISE.

Descriptive Note : Technical memo.,

Corporate Author : HUMAN ENGINEERING LABS ABERDEEN PROVING GROUND MD

Personal Author(s) : Hodge,David C. ; McCommons,R. Bruce

Report Date : JUL 1967

Pagination or Media Count : 24

Abstract : The sound-shadow effect of the human head in an impulse-noise field was studied by exposing 27 subjects to gunfire noise so their left ears were normal to the oncoming shock wave (near ear) and their right ears were protected by the shadow of the head (far ear). Noise exposure was continued until the subject's near ear demonstrated 15 dB temporary threshold shift (TTS) and the post-exposure TTS in near and far ears was compared. Peak pressure level at the entrance of the far ear canal was less than one-half that found at the near ear (153 vs. 161 dB re 0.0002 microbar). Mean TTS was significantly smaller in the far ears than it was in the near ears. The mean 'protection' afforded the far ear by the head's shadow ranged from three dB at 1 kHz to 12 dB at 6 kHz. The implications of the findings for the protection of weapon crewmen are discussed. (Author)

Descriptors :   (*EAR, *HEARING), (*COMBAT NOISE, *SHOCK WAVES), SOUND, PROTECTION, WEAPONS, ACOUSTICS, WEAPON SYSTEMS, GUNS, HUMAN FACTORS ENGINEERING, PHYSIOLOGY

Subject Categories : Anatomy and Physiology
      Acoustics
      Human Factors Engineering & Man Machine System

Distribution Statement : APPROVED FOR PUBLIC RELEASE