Evoked-response forward-masking functions in chinchillas with noise-induced permanent hearing loss.
Arehole-S; Salvi-RJ; Saunders-SS; Gratton-MA
Audiology 1989 Mar; 28(2):92-110
Measurements were made of the evoked response forward masking functions in the inferior colliculus of ten normal chinchillas before and after creating a noise induced permanent threshold shift (PTS). The mean preexposure thresholds of the ten animals ranged from 3 decibels (dB) sound pressure level (SPL) at 0.5 kilohertz (kHz) to 24dB SPL at 16kHz. The evoked response thresholds were remeasured about 30 days after the exposure. The forward masking functions were changed in frequency regions where there was a significant hearing loss. This hearing loss resulted in an increase in the time constant of forward masking. This increase was particularly noted once the threshold shift exceeded 20dB. The possibility of a relationship between the change in the time constant and the degree of hearing loss, the ratio of the post to preexposure time constraint was computed and plotted as a function of hearing loss at each frequency. Small amounts of hearing loss had little effect on the forward masking time constants. Once the hearing loss exceeded approximately 25dB, the tau ratio increased rapidly.
NIOSH-Publication; NIOSH-Grant; Noise-induced-hearing-loss; Industrial-noise; Laboratory-animals; Noise-exposure; Sensory-thresholds; Hearing-threshold; Auditory-system; Hearing-impairment
State University of New York, Buffalo, New York