Correlates of tone-on-tone masked thresholds in the chinchilla auditory nerve.

In an attempt to determine neural correlates of tone-on-tone masking, discharge patterns of chinchilla auditory-nerve fibers were obtained in response to a set of two-tone stimuli for which behavioral masking had been previously measured (Long, G.L. and Miller, J.D. (1981): Hearing Res. 4, 279-285). The lowest masked thresholds in a sample of fibers were quantitatively similar to the chinchilla's behavioral masked thresholds. In addition, the neural data were in qualitative agreement with other previously-described characteristics of tone-on-tone masking, such as the contribution of cochlear distortion products and the upward spread of masking. It thus appears that the limitations imposed by peripheral frequency analysis determine the tone-on-tone masking pattern.