Noise-induced cochlear damage assessed using electrophysiological and morphological criteria: an examination of the equal energy principle.

Cochlear damage immediately following exposure to continuous pure tones of varying intensity and duration was assessed in anaesthetized guinea pigs. Indices of damage used were elevation of N1 thresholds and severity of swelling of the afferent dendrites beneath the inner hair cell. The results were not wholly consistent with the assumptions of the equal energy principle. Longer duration exposures resulted in greater N1 threshold elevation and more severe swelling of dendrites than short exposures of the same total energy.