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Impulse Noise Induced Hearing Loss from Simulated Work-Week Exposures.

PB91185207

Publication Date	1991
Personal Author	Henderson, D.; Hamernik, R. P.; Hynson, K.
Page Count	26
Abstract	After preexposure thresholds had been determined, six adult monaural chinchillas were exposed to a repetitive, reverberant impulse for 8 hours per day, for 5 days. The noise impulses were produced by two automated, cam driven, brass hammers hitting a steel plate. Thresholds were measured at 0.25, 0.5, 1, 2, 4, and 8 kilohertz (kHz) 0.5 hour before and 0.5 hour after each of the five 8-hour exposures. After the last exposure the recovery of threshold was monitored for 5 successive days. Final hearing thresholds were obtained starting at 30 days postexposure and were either the average of 3 days of averaged evoked response (AER) testing or 10 days of behavioral testing. The AER thresholds were systematically higher than the behavioral thresholds by 5 to 18 decibels. All frequencies were shifted by approximately the same amount by the end of the 5-day exposure as they were at the end of the first day's exposure, and there was no cumulative effect. There was still some residual threshold shift with 2 days' recovery. The actual degree of oscillation of threshold presumably would be a function of the actual noise exposure as well as the acoustic environment during recovery.
Keywords	Hearing loss Occupational exposure Noise Chinchilla Auditory threshold Audio frequencies Auditory evoked potentials Tests Laboratory animals
Source Agency	National Institute for Occupational Safety and Health
NTIS Subject Category	94D - Job Environment 44G - Environmental & Occupational Factors 68B - Noise Pollution & Control 57S - Physiology
Corporate Authors	State Univ. of New York Upstate Medical Center, Syracuse.; National Inst. for Occupational Safety and Health, Cincinnati, OH.
Supplemental Notes	Portions of this document are not fully legible. Sponsored by National Inst. for Occupational Safety and Health, Cincinnati, OH.
Document Type	Technical Report
NTIS Issue Number	199115

Impulse Noise Induced Hearing Loss from Simulated Work-Week Exposures.

Impulse Noise Induced Hearing Loss from Simulated Work-Week Exposures.
PB91185207

Publication Date	1991
Personal Author	Henderson, D.; Hamernik, R. P.; Hynson, K.
Page Count	26
Abstract	After preexposure thresholds had been determined, six adult monaural chinchillas were exposed to a repetitive, reverberant impulse for 8 hours per day, for 5 days. The noise impulses were produced by two automated, cam driven, brass hammers hitting a steel plate. Thresholds were measured at 0.25, 0.5, 1, 2, 4, and 8 kilohertz (kHz) 0.5 hour before and 0.5 hour after each of the five 8-hour exposures. After the last exposure the recovery of threshold was monitored for 5 successive days. Final hearing thresholds were obtained starting at 30 days postexposure and were either the average of 3 days of averaged evoked response (AER) testing or 10 days of behavioral testing. The AER thresholds were systematically higher than the behavioral thresholds by 5 to 18 decibels. All frequencies were shifted by approximately the same amount by the end of the 5-day exposure as they were at the end of the first day's exposure, and there was no cumulative effect. There was still some residual threshold shift with 2 days' recovery. The actual degree of oscillation of threshold presumably would be a function of the actual noise exposure as well as the acoustic environment during recovery.
Keywords	Hearing loss Occupational exposure Noise Chinchilla Auditory threshold Audio frequencies Auditory evoked potentials Tests Laboratory animals
Source Agency	National Institute for Occupational Safety and Health
NTIS Subject Category	94D - Job Environment 44G - Environmental & Occupational Factors 68B - Noise Pollution & Control 57S - Physiology
Corporate Authors	State Univ. of New York Upstate Medical Center, Syracuse.; National Inst. for Occupational Safety and Health, Cincinnati, OH.
Supplemental Notes	Portions of this document are not fully legible. Sponsored by National Inst. for Occupational Safety and Health, Cincinnati, OH.
Document Type	Technical Report
NTIS Issue Number	199115