AP threshold elevation in the guinea pig following exposure to a broadband noise.
Sixty guinea pigs were exposed to a steady-state broadband noise with a falling frequency spectrum. The sound-pressure level was varied between 96 and 117 dB SPL, and the duration of the exposure was varied from 3 to 12 h. After 4-5 weeks, the auditory thresholds were determined by electrocochleography at 14 frequencies, and the results were compared with a control group. With increasing sound-pressure level, the thresholds became elevated at all frequencies. The maximum threshold elevation also exhibited a slight shift toward higher frequencies. With increasing exposure time, the threshold elevations increased and shifted into the high-frequency region, whereas the low-frequency region was less affected. Linear regression analysis showed that the average threshold elevation between 1 and 20 kHz did not deviate from that predicted by the equal-energy hypothesis. However, the high-frequency loss at 5-20 kHz was very dependent on the exposure time, whereas the 1- to 4-kHz loss was not. There was no sign of any critical intensity with sudden increments in threshold elevation.
Grenner
J
J
Department of Otolaryngology and Experimental Research, University of Lund, Malmö General Hospital, Sweden.
Nilsson
P
P
Katbamna
B
B
D000818:Animals; D001309:Auditory Threshold; D005260:Female; D006168:Guinea Pigs; D009622:Noise