Relationships between cochlear pathologies and auditory nerve and behavioral responses following acoustic trauma.
Salvi-R; Perry-J; Hamernik-RP; Henderson-D
New perspectives on noise-induced hearing loss. Hamernik RP, Henderson D, Salvi R, eds. New York: Raven Press, 1982 Jan; :165-188
The relationship between psychophysical measures and the discharge patterns of single auditory nerve fibers was examined in regard to the effects of intense noise exposure. Five chinchillas were exposed for 5 days to octave band noise centered at either 4 or 0.5 kilohertz and having sound pressure levels of 86 and 95 decibels (dB), respectively. Psychophysical tuning curves were obtained using a simultaneous masking procedure. Single fiber tuning curves were made using 20 millisecond tone bursts, and thresholds were estimated with audiovisual criteria. Two tone inhibition was studied using a frequency near the unit's characteristic frequency and one that was approximately 10 to 15dB higher than threshold. Acute exposure to high frequency noise induced asymptotic temporary threshold shifts approximating 60 to 70dB at frequencies greater than 4 kilohertz. A permanent threshold shift of 15 to 20dB was noted after 7 months of recovery time. Low frequency threshold units were unaffected. Behavioral and neural threshold data were positively correlated in the high frequency noise exposure group. Two tone inhibition was affected when either tone occurred in a frequency region in which there was a loss of sensitivity. Acute exposure to low frequency noises resulted in an asymptotic temporary threshold shift varying between 30 and 70dB over the entire range of hearing. Permanent threshold changes of 18 and 20dB were noted at 30 days and 2 years post exposure, respectively, at the midfrequency range. The results were discussed with regard to hair cell loss and implications for behavioral and neural tuning in humans.
NIOSH-Grant; Noise-induced-hearing-loss; Acoustical-measurements; Ear-disorders; Noise-levels; Laboratory-animals; Neuropathology; Neurophysiological-effects; Cell-damage
Callier Ctr/communic Disorders Callier Center 1966 Inwood Road Dallas, Tex 75235
Hamernik-RP; Henderson-D; Salvi-R
New perspectives on noise-induced hearing loss
University of Texas Dallas, Richardson, Texas