The relation among hearing loss, sensory cell loss and tuning characteristics in the chinchilla.
Davis RI; Ahroon WA; Hamernik RP
Hear Res 1989 Aug; 41(1):1-14
The relationships between changes in frequency selectivity, sensory cell loss, and hearing loss were examined using auditory evoked potential (AEP) tuning curves (TC) in 154 chinchillas. AEP techniques were used to obtain pure tone thresholds at 0.5, 1.0, 2.0, 4.0, 8.0, and 11.2 kiloHertz (kHz). Various noise exposures resulted in permanent threshold shifts (PTS) ranging from 0 to 50 decibels (dB) at 30 to 40 days post exposure. Cytocochleograms were prepared for each animal after threshold testing was completed. TC were analyzed in terms of TC variables and low and high frequency slopes. For PTS less than 10dB, TC variables were nearly identical before and after noise exposure. All three TC variables examined exhibited systematic changes for PTS greater than 10dB. The percentage change in mean TC variables was also correlated with a loss of outer hair cells at all probe tone frequencies except for 8.0 and 11.2kHz. The authors conclude that progressive hearing losses are associated with changes in the quality of tuning and with losses of outer hair cells.
NIOSH-Publication; NIOSH-Grant; Noise-induced-hearing-loss; Laboratory-animals; Noise-exposure; Audiofrequency; Hearing-threshold; Ear-disorders; Auditory-system
Communicative Disorders & Scis Research Foundation of Suny P O Box 9 Albany, N Y 12201
Plattsburgh State University, New York