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Industrial noise: potentiating interactions.

Ahroon WA
Auditory Research Laboratory, State University of New York, Plattsburgh, New York, Report No. ARL 88-1 1988 Apr; :1-539
Using a 5 day exposure paradigm to produce an asymptotic threshold shift, measurements were taken of preexposure and postexposure hearing thresholds for 94 chinchillas. The exposures were designed to be realistic for industrial environments containing both impulse and continuous noise sources. Octave bands of noise centered at decibels (dB) sound pressure level (SPL), respectively, or with impact noises of 113, 119, or 125dB SPL presented once per 1, 4, or 16 seconds, respectively, were used as the exposure conditions for six control groups. Animals in nine interaction groups and exposed to combinations of one of the above impulse and continuous noise sources. An exacerbation of hearing loss and sensory cell loss was noted in animals exposed to the 119 and 125dB impacts in combination with the low frequency and middle frequency continuous noises, even though attempts were made to balance each of the different sets of combined exposures which contained impulsive noises of a given peak SPL to produce exposures of equal energy. As the spectral overlap between the impact and continuous noises was lessened, and as the total energy of the combined exposures was lowered, this interaction effect disappeared. A very notable reduction was obtained in the frequency selectivity of the auditory system, as measured by the auditory evoked potential tuning curves, as the amount of permanent threshold shift increased. The author concludes that interactions between different types of noise can exacerbate hearing loss following exposure. Adequate predictions of danger may not be obtained by the equal energy hypothesis when exposures consist of complex combinations of types of noise.
NIOSH-Grant; Noise-induced-hearing-loss; Hearing-loss; Industrial-noise; Impulse-noise; Laboratory-animals
Communicative Disorders & Scis Research Foundation of Suny P O Box 9 Albany, N Y 12201
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Auditory Research Laboratory, State University of New York, Plattsburgh, New York, Report No. ARL 88-1
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Plattsburgh State University, New York
Page last reviewed: April 12, 2019
Content source: National Institute for Occupational Safety and Health Education and Information Division