Further evidence of acoustic invariance in speech production: the stop-glide contrast.
We have conducted a detailed comparative acoustic analysis of the labial stop and glide, [b] and [w], and we have attempted to identify an invariant acoustic property which can accurately distinguish stops and glides. To this end, we conducted three experiments. In experiment I, we undertook computer analysis of the labial stop [b] and the labial glide [w] as produced in five vowel contexts by two speakers. Results indicated that transition durations and formant frequencies often differed considerably in these two classes of sounds--and to a much greater extent than suggested in previous perception experiments. In experiment II we examined a measure of amplitude--unit energy. We calculated the degree of relative amplitude change occurring in the vicinity of the stop and glide release and found reliably larger changes in energy associated with the stop release than the glide release across vowel contexts and speakers. These changes seemed to provide an invariant property characterizing the stop--glide contrast. In experiment III we tested the generality of our claims by examining a new set of data consisting of the stops [d] and [g] and the glide [y]. Results of this experiment further supported our hypothesis. We have related our findings to a general theory of acoustic invariance in speech.
D006801:Humans; D008046:Lip / Q000502:physiology; D008297:Male; D010700:Phonetics; D013018:Sound Spectrography; D013060:Speech / Q000502:physiology; D013061:Speech Acoustics; D013067:Speech Perception; D013997:Time Factors