The effect of group delay spectrum on timbre.

Abstract

This paper describes the results of subjective experiments investigating the characteristics of human phase perception. In these experiments, the stimuli have a flat amplitude spectrum and a group delay spectrum that has a single peak described by a Gaussian function where the mean (center frequency) and the standard deviation (bandwidth) are free parameters of interest. The first experiment was performed using stimuli with different peak values, where the center frequencies are fixed at 1,000 Hz and 4,000 Hz, and the bandwidths are also fixed. These bandwidths are computed by weighting the equivalent rectangular bandwidth (ERB) with certain parameters. It was found that when the peak values of the stimuli are between -1 ms and 2 ms, they are perceived to be zero phase, regardless of their center frequencies and bandwidths. Moreover, when the peak values of the stimuli are less than -8 ms or more than 10 ms and the bandwidths are less than 1 ERB, they are perceived to be similar. This result indicates that the nonzero-phase stimuli are similar when the bandwidth is less than 1 ERB. It was also found that the similarity of the stimuli reduces when the bandwidths of the nonzero-phase stimuli are more than 1 ERB.