Cochlear Hair-Cell Damage in Guinea Pigs after Exposure to Impulse Noise

Fourteen young guinea pigs were individually exposed to 500 rounds of paper “caps” tired in a toy gun at a distance of 30 cm. The gun was fired at intervals of 1 5 sec. After seven weeks survival, the cochleas were removed and each complete organ of Corti examined, using Engström's surface-preparation technique. Cochleograms (tabular forms showing position and condition of each cell) were prepared for each row of hair cells. Curves were plotted showing number of damaged cells as a function of distance from the base. In approximately 80% of the cases, total destruction of hair cells occurred in a narrow band midway along the organ of Corti. The severity and distribution of damage for the group are compared with similar data for another group, which was exposed to high-intensity pure tones.