Impulse Noise Trauma: A Study of Histological Susceptibility

Abstract

The integrity of the organ of Corti after exposure to high intensity impulse noise was studied using the chinchilla and guinea pig. Animals were exposed to three levels of impulses (166-, 161-, or 155-dB peak sound pressure level) having a 1-msec A-duration. Evoked-response audiometry and the surface preparation techniques were used to obtain both audiometric and histological data from one half hour to 50 days after exposure. The data indicate that (1) lower (155-dB peak SPL) intensities are potentially more hazardous to the hair cell population than the higher intensities and (2) there exists a critical intensity and duration (approximately 161-dB peak SPL and 1 msec A-duration) above which individual susceptibility precludes any confident histological comparison across animals. Failure of the conductive mechanism is presumed to be responsible for this large histological variability.