Hazard from weapons impulses: histological and electrophysiological evidence.
Price-GR; Kim-HN; Lim-DJ; Dunn-D
J Acoust Soc Am 1989 Mar; 85(3):1245-1254
Histological data was presented from studies with 51 adult cats exposed to either rifle or howitzer impulses on one occasion at peak pressures (145 to 155 decibels (dB) or 153 to 166dB, respectively). The electrophysiological effects were related to the histological measures, and the theoretical and practical implications are discussed. Histological measurements were carried out 2 months after the exposures occurred. For both types of impulse the losses tended to be in the middle of the cochlea in focused lesions, even though the spectral peaks of the acoustic stimuli had been at about 80 hertz (Hz) for the howitzer and 1000Hz for the rifle. More susceptibility was noted among the outer hair cells than the inner hair cells and interindividual differences in effects were large. The two impulse sources were equally hazardous when the peak pressure of the rifle impulse was lower than the peak pressure of the howitzer impulse by about 9dB. In terms of dB-A weighted energy, the exposures were equally hazardous when the rifle exposure contained about 35 times less energy than the howitzer exposure. The histological data were consistent with the electrophysiological data, which indicated that present standards for impulse noise exposure may overrate the hazard of low frequency impulses relative to impulses in the midrange.
NIOSH-Author; Military-personnel; Noise-exposure; Ear-disorders; Impulse-noise; Explosions; Cell-damage; Physiological-response; Acoustical-measurements
Journal of the Acoustical Society of America