Hearing loss in the chinchilla from impact and continuous noise exposure

• Published in: The Journal of the Acoustical Society of America Vol. 90; no. 4 Pt 1; p. 1979
• Main Authors: Dunn, D E, Davis, R R, Merry, C J, Franks, J R
• Format: Journal Article
• Language: English
• Published: United States 01.10.1991
• Subjects: Animals; Auditory Cortex - physiopathology; Auditory Fatigue - physiology; Auditory Threshold - physiology; Chinchilla; Hearing Loss, Noise-Induced - physiopathology; Loudness Perception - physiology; Noise - adverse effects; Pitch Perception - physiology; Sound Spectrography
• ISSN: 0001-4966; 1520-8524
• DOI: 10.1121/1.401677

The relative hazard posed to the peripheral auditory system by impact/impulse and continuous noise of the same power spectrum was determined. Impact noise was generated by striking a nail with a hammer and was digitally recorded. The acoustical power spectrum of the impact was determined and pink noise was filtered to produce a continuous noise stimulus with the same acoustic power spectrum. Pre-exposure auditory evoked response (AER) thresholds were obtained at 1, 2, 4, and 8 kHz on 16 adult chinchillas. The pool of animals was divided into two equal groups based upon pre-exposure AER thresholds. One group was exposed to impact noise and the other group to the filtered pink noise. Exposures were 4 h/day for 5 days. Thirty days following the exposure, auditory evoked response thresholds were remeasured. Changes in auditory sensitivity were determined by subtracting the pre-exposure thresholds from the post-exposure thresholds. Hearing threshold shifts of the impact noise group were significantly greater (p less than 0.0001) than the hearing threshold shifts of the continuous noise group. These data indicate a need to more closely examine the parameters and effects of impact noise. There may be a need to develop expanded damage-risk criteria for occupational exposure to impulse/impact noise.