Rate versus level functions for auditory-nerve fibers in cats: Bandlimited noise bursts

Abstract

We will generalize our previous description of the responses to two-tone stimuli to allow the prediction of responses to continuous spectrum stimuli. For noise bursts of one bandwidth and center frequency, discharge rate was measured as a function of spectral level. Such rate-level functions were measured for a number of noise bandwidths; either the low- or high-cutoff frequencies were set at fiber characteristic frequency. Narrow bands of noise produce rate-level functions similar to those for CF tones. For noise bands centered above CF, rate-level functions become less steep as bandwidth is increased and approach the same saturation rate as that produced by CF tones. For wide bands of noise centered below CF, rate-level functions can be nonmonotonic or appear to plateau at rates less than the saturation rate to CF tones. Thus, bands centered either above or below CF can produce lower discharge rates than do narrow bands of the same spectral level. This rate reduction has properties similar to those of two-tone suppression. [Supported by NINCDS and NINGMS.]