Perception of frequency‐lowered vowels by naive listeners

Abstract

The effect of frequency‐lowering on the perception of vowels (in /b/‐V‐/t/ contexts) by naive listeners was studied using an identification paradigm. The stimuli consisted of 16 vowels and diphthongs processed by a variety of techniques (including time dilation, frequency warping, and linear prediction) to achieve pitch‐variant and pitch‐invariant lowering combined with both uniform (proportional) and nonuniform (warped) compression of the frequency axis. Lowpass filtering conditions were also included for comparison purposes. Perceptual confusions were analyzed in terms of articulatory features. In general warped frequency lowering (which primarily compressed the higher frequencies) resulted in a differential degradation of feature perception, while proportional lowering degraded the features more uniformly. Lowering fundamental frequency by a factor of two had more severe effects on the perception of vowels spoken by males than by females. Also, lowering both fundamental and formant frequencies of female vowels failed to make them as resistant to lowpass filtering as male vowels. [Work supported by NIH.]