Explaining the intrinsic pitch of vowels

Abstract

The reason why, other things being equal, the pitch of vowels correlates with vowel “height,” has long been a subject of speculation. The effect is usually attributed either to acoustic coupling between vocal tract and vocal cords or to the pull of the tongue on the vocal cords. To determine which of these hypothesized factors is responsible we observed the effect on the pitch of vowels when one of these factors (impedance of the vocal tract was held constant, while the other (tongue stretch) was varied over an exaggerated range, viz., by having eight speakers utter special test utterances when their jaw was propped open by small wooden blocks ⩽ 10 mm thick. (Lindblom and Sundborg have shown that under such conditions apeakers can achieve acoustically normal vowels by increasing the distortion—and presumably the stretch—of the tongue body with respect to the jaw and larynx-hyoid complex.) We found a small but consistent increase in the pitch interval between high and low vowels when subjects spoke with propped-open jaw, thus supporting the “tongue-pull” hypothesis. [Supported by NSF.]