CONFOCAL MICROSCOPIC ANALYSIS OF THE CHINCHILLA ORGAN OF CORTI FOLLOWING EXPOSURE TO HIGH-LEVEL IMPACT NOISE

To better understand the nature of mechanical changes following exposu re to high-level impact noise, normal cochleas and cochleas from chinc hillas exposed to either 125 or 131 dB SPL noise were stained with pha lloidin for F-actin and examined using confocal microscopy. As seen in previous experiments, 125 dB exposures produced much more variable re sults than 131 dB exposures. Some cochleas were relatively unscathed b y the exposure, whereas others showed damage to outer hair cells (OHCs ) immediately after the exposure that included gross distortions of ce ll bodies and reduced F-actin in cuticular plates. Twenty-four hours l ater, there was also disorientation of actin filaments in supporting c ells. After 30 days, Deiters cells were disarrayed and cups were separ ated from OHC neural poles. Exposure to noise at a level of 131 dB SPL produced less variable results than 125 dB exposure, and damage was g enerally more widespread and severe.