NRL Technical Year End Progress Report for MCSC PM-ICE FY11 SOW Tasks 1 and 2 - Hearing Loss

A human surrogate was recently developed to emulate the acoustic transmission path of a human ear. This physical model was used to study soldier exposure to impulsive small weapons fire. The ear response of the surrogate and human data are in very good agreement. The effect of the helmet and body ar...

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Bibliographic Details
Main Authors: Herdic, Peter C, McMahon, James W, Amon, Daniel L, Dzikowicz, Benjamin R, Houston, Brian H, Hubler, Graham K
Format: Report
Language:English
Subjects:
ANATOMICAL MODELS
Anatomy and Physiology
Biomedical Instrumentation and Bioengineering
EAR
HEARING
HEARING LOSS
HUMAN EAR SURROGATE
Optics
SHOOTER'S NOTCH
SHOT NOISE
SMALL WEAPONS FIRE
SOUND PRESSURE
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Summary:A human surrogate was recently developed to emulate the acoustic transmission path of a human ear. This physical model was used to study soldier exposure to impulsive small weapons fire. The ear response of the surrogate and human data are in very good agreement. The effect of the helmet and body armor equipment on a soldier's hearing was determined in this report through laboratory and firing range measurements. A sound pressure level (SPL) reduction of 2 to 3 dB on both left and right inner ears of the surrogate was found when a helmet was worn. This reduction was probably due to the helmet blocking the direct acoustic path from the weapon muzzle to the ear. Body armor appears to have very little effect on the sound reaching the inner ears. This implies that reflections from the torso are a second order effect when compared to the direct acoustic path. The physics of the direct acoustic path from the weapon muzzle to the ears appears to be the most important acoustic mechanism affecting the inner ear SPL levels. The surrogate developed here may serve as a standard for human hearing evaluation of infantry combat equipment and weapons systems deemed relevant to the warfighter. The original document contains color images.