Differential susceptibility of avian hair cells to acoustic trauma.

Five groups of 10-day-old chicks were continuously exposed to either 500 or 1500 Hz pure tone at 125 dB for 4 or 12 h and killed 10 days later. The basilar papillae were fixed, embedded in plastic, sectioned, and hair cells were counted according to type: tall or short. Short hair cells were found to be more susceptible to acoustic overstimulation than tall hair cells. Further, the position of maximum short hair cell loss varied along the length of the basilar papilla as a function of the exposure frequency while the position of tall hair cell loss did not. Similarities between morphological response of short hair cells in avians after acoustic trauma and outer hair cells in mammals are discussed.