Reversal of relationship between impression of voice pitch and height of fundamental frequency: Its appearance and disappearance

Abstract

This study investigated the cognitive biases related to the impression of voice pitch caused by changes in tonal quality. According to the vocal tube model, changing the vocal-tract length (VTL) systematically alters the tonal quality. In one experiment, the fundamental frequency (f_o) of the speech samples was raised and lowered on a mel-scale axis. Then the spectral-frequency scale was expanded and contracted to simulate reducing and increasing the VTL. In a second experiment, the width of the f_o range was changed in addition to changing the f_o height and VTL scaling. Noise-vocoded speech samples were generated to measure the independent effects of the VTL scaling. The participants rated their impressions of the pitch using paired comparison. The results revealed a reversal of the relationship between impression of voice pitch and height of f_o when the effects of f_o height and VTL scaling on pitch impression were opposite to each other and when the range of the f_o contour was equivalent to that of natural speech. VTL scaling played a dominant role in this reversal. However, as the f_o contour became flat, this reversal phenomenon disappeared, and the f_o height factor came to play the dominant role.