Threshold Shifts Produced by Exposure to Noise in Chinchillas with Noise-Induced Hearing Losses Monaural chinchillas (N = 4), with permanent hearing losses caused by previous noise exposures, were exposed in a diffuse sound field to an octave-band noise (centered at 4.0 k Hz) at 80 dB SPL. The controls were normal-hearing chinchillas (N = 16) who had been exposed under identical conditions in ... Research Article
Research Article  |   December 01, 1973
Threshold Shifts Produced by Exposure to Noise in Chinchillas with Noise-Induced Hearing Losses
 
Author Affiliations & Notes
  • John H. Mills
    Central Institute for the Deaf, St. Louis, Missouri
Article Information
Research Articles
Research Article   |   December 01, 1973
Threshold Shifts Produced by Exposure to Noise in Chinchillas with Noise-Induced Hearing Losses
Journal of Speech, Language, and Hearing Research, December 1973, Vol. 16, 700-708. doi:10.1044/jshr.1604.700
History: Received June 20, 1973 , Accepted October 22, 1973
 
Journal of Speech, Language, and Hearing Research, December 1973, Vol. 16, 700-708. doi:10.1044/jshr.1604.700
History: Received June 20, 1973; Accepted October 22, 1973

Monaural chinchillas (N = 4), with permanent hearing losses caused by previous noise exposures, were exposed in a diffuse sound field to an octave-band noise (centered at 4.0 k Hz) at 80 dB SPL. The controls were normal-hearing chinchillas (N = 16) who had been exposed under identical conditions in previous experiments. Auditory thresholds were measured during the course of the five-day exposure at postexposure times of four to 11 minutes. When the duration of exposure was greater than two hours, shifted thresholds (SPL at threshold) for nearly all audible frequencies were essentially the same for those chinchillas with normal hearing as for those with impaired hearing. Threshold shifts were always smaller in the experimental group. While thresholds for both the normal-hearing and hearingimpaired subjects increased only during the first 24 hours of exposure, the shape of the growth curves for the hearing-impaired subjects was marked by irregularities.

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