Complex noise exposures: an energy analysis.
Ahroon-WA; Hamernik-RP; Davis-RI
J Acoust Soc Am 1993 Feb; 93(2):997-1006
A series of experiments was conducted to investigate the hazard to hearing from complex noise exposures to determine if the equal energy hypothesis can unify the results from combinations of continuous noise and moderate levels of impact noise exposures of a type that often occur in industrial work environments. Chinchillas were exposed for 5 days to one of several different noise exposure conditions consisting of either octave bands of noise, impact alone, or combinations of impact and octave bands of noise. The noise induced trauma was measured by monitoring the evoked potential of hearing thresholds and cochleograms. For sound exposure levels which produce less than approximately 10 decibels (dB) of permanent threshold shift, or 5% total sensory cell loss, equal energy exposures tended to produce equivalent effects on hearing. There was a range of at least 10dB in the sound exposure level (SEL) parameter where hearing loss from equal energy exposures at a particular SEL could be exacerbated by increasing the repetition rate of the impacts or by the addition of a Gaussian low level noise. The exacerbation of trauma from the addition of a Gaussian continuous noise was dependent on the spectrum of that noise.
NIOSH-Publication; NIOSH-Grant; Noise-induced-hearing-loss; Noise-exposure; Hearing-loss; Laboratory-animals; Ear-disorders; Sensory-thresholds; Hearing-threshold
Communicative Disorders & Scis Research Foundation of Suny P O Box 9 Albany, N Y 12201
Journal of the Acoustical Society of America
State University of New York at Buffalo, Buffalo, New York