The potentiation of noise by other ototraumatic agents.
Effects of noise on hearing. Henderson D, Hamernik RP, Dosanjh DS, Mills JH, eds. New York: Raven Press, 1976 Jan; :291-307
The combined effects of drugs and noise or of different types of noise on cochlear pathologies and hearing loss in animals and man were reviewed. One class of ototoxic drugs included those producing temporary threshold shift, and another, including aminoglycoside antibiotics, caused permanent impairment. The nature of the potentiation of noise damage by aminoglycosides appeared to be a general cochlear process that predisposed the cochlea to damage from low and high frequency and from impulse noise. The effects of salicylates were believed to be temporary and did not potentiate noise induced changes. The idea that the audiometric effects of impulse noise are the same as of continuous noise has been questioned. The equal energy principle did not work for impulse noise in interaction with continuous noise at a low level of the intensity scale. When impulse and continuous noise exposures were combined in chinchillas, it was observed that for a 95 decibel (dB) 2 to 4 kilohertz (kHz) 1 hour long exposure, the impulse had to be between 137 and 142dB per sound pressure level (SPL) to initiate a significant interaction effect. When continuous 2 to 4kHz background noise was decreased from 95 to 89dB SPL, the interaction effect with 158dB impulse noise persisted. After 2 hours postexposure, the 89dB group began to recover rapidly and was near normal threshold by 400 hours. However, the 95dB group had a 30dB permanent threshold shift after 30 days. Data from studies of noise exposed military personnel or industrial workers have provided support for the concept of a continuous noise/impulse noise interaction. The authors conclude that the interaction between impulse and continuous noise is potentially dangerous and that special consideration should be given to this interaction when evaluating a given noise environment.
NIOSH-Grant; Laboratory-animals; Hearing-impairment; Auditory-system; Synergism; Drug-interaction; Noise-induced-hearing-loss; Physiological-response; Acoustic-trauma; Inner-ear
Henderson-D; Hamernik-RP; Dosanjh-DS; Mills-JH
Effects of noise on hearing
Upstate Medical Center, Syracuse, New York