Detection of temporal changes in the pitch of complex stimuli

Abstract

The repetition pitch of ripple noise was temporally varied to determine the relationship between the rate of pitch variation and the perception of pitch change. Listeners were asked to discriminate between flat spectral noise and ripple noise whose ripple density was temporally varied in a sinusoidal manner. The spectrum of the temporally varying ripple noise stimulus was 1 + m cos{2f[g(T)]}; where f is frequency, m is the modulation depth of the spectral ripple, and g(T) = T + T sin 2ft, where T is the delay used to generate ripple noise, T is the range of pitch change, f is the rate (Hz) of pitch change, and t is time. The repetition pitch of ripple noise is directly related to the delay, T. At each rate of pitch variation the depth of modulation (m) was varied in the adaptive, forced‐choice task until the listener was at 71% correct in his or her ability to discriminate ripple noise from flat noise. For a variety of conditions the results indicate that listeners are unable to detect the change in the pitch of ripple noise at rates of pitch change that exceed 2–5 Hz. This in turns implies that the auditory system is slow (200–500 ms estimated integration time) in its ability to process the complex stimulus of ripple noise. [Work was supported by the National Science Foundation.]