The effect of high level sound on hearing sensitivity, cochlear sensorineuroepithelium and vasculature of the chinchilla.

Ten young chinchilla were tested for hearing and then exposed for 8 hours to a 110 dB (SPL) broad-band noise. Post-stimulation recovery was assessed daily until permanent threshold shifts were obtained. Cochlear tissues were prepared in order to allow viewing of sensory cells as well as the vascular supply of the cochlea. Findings included inconsistent displacement of the vestibular membrane, poor injection of a contrast medium into vessels, moderate outer hair cell loss and displaced inner hair cell nuclei. Small basal turn cell damage was accompanied by greater than expected losses for high frequency pure tones.