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Asymptotic threshold shift in chinchillas exposed to impulse noise.

Authors
Blakeslee-EA; Hynson-K; Hamernik-RP; Henderson-D
Source
Department of Otolaryngology and Communication Sciences, State University of New York, Upstate Medical Center, Syracuse, New York, 1981 Jan; :1-31
Link
NIOSHTIC No.
00197926
Abstract
In an effort to more fully understand the results of long term exposures to impulse noise as they relate to asymptotic threshold shift (ATS), five monaural chinchillas were exposed to a repetitive, reverberant impulse noise for 10 days. The noise was generated by a mechanized hammer hitting a steel plate at the rate of one beat per second. The average peak over pressure within the holding cage was 113 decibels (dB) sound pressure level. Auditory thresholds were measured before exposure. Similar measurements were taken at 0.5, 1, 1.4, 2, 2.8, 4, 8, and 16 kilohertz (kHz) using shock avoidance conditioning. Thresholds were monitored on a daily basis during exposure at 0.5 and 8kHz. Threshold shift at 8kHz had reached an asymptotic level within 1 hour from the start of the exposure while threshold shift at 0.5kHz leveled off after 24 hours of exposure. ATS levels for both frequencies varied between 30 to 50dB across animals. By 40 days after exposure the median threshold shift for both frequencies recovered to within 10dB of normal. Maximum permanent threshold shift was at 2 and 2.8kHz with median PTS of 17 and 13dB, respectively. The cochleas were examined histologically. The stability of the ATS produced by impulse noise and the consistency across the five animals suggest that the phenomenon may be useful in the systematic study of both temporary threshold shift and noise induced permanent threshold shift.
Keywords
NIOSH-Grant; Noise-induced-hearing-loss; Noise-exposure; Laboratory-animals; Hearing-threshold; Sensory-thresholds
Contact
Otolaryngology Upstate Medical Center Departm 750 E Adams Street Syracuse, N Y 13210
Publication Date
19810101
Document Type
Final Grant Report
Funding Amount
651569
Funding Type
Grant
Fiscal Year
1981
NTIS Accession No.
PB91-188847
NTIS Price
A04
Identifying No.
Grant-Number-R01-OH-00364
NIOSH Division
OEP
Priority Area
Noise-induced-hearing-loss
Source Name
Department of Otolaryngology and Communication Sciences, State University of New York, Upstate Medical Center, Syracuse, New York
State
NY
Performing Organization
Upstate Medical Center, Syracuse, New York
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