A study on perceptual distance measure for phase spectrum of stimuli

This paper describes a perceptual distance measure for phase spectrum based on results from a subjective experiment using stimuli. The stimuli have flat amplitude spectrum and, in a particular frequency band, have a certain group delay value. The experiment was performed using stimuli with different group delay peak values where the group delay center frequencies are fixed, and their associated group delay bandwidths are also fixed. It was found that when the peak values of 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 are less than -8 ms or more than 10 ms and the bandwidths are less than 1 ERB, each of the stimuli are perceived to be similar. Based on these perceptual similarity results, we introduce an ellipsoidal function to estimate the similarity scores with a simple equation. It is found that the estimated similarity scores well approximate the subjective similarity scores