Phonetics of intervocalic consonant perception: retrospect and prospect

This article reviews the production characteristics and perceptual cues of intervocalic consonants as a background for acoustic studies of consonant perception in fluent speech. Data show that in conversation intervocalic consonants occur much more commonly than consonants in initial or final position; all phonetic features are strongly represented. Production characteristics of intervocalic consonants are seen to depend on the tempo and rhythmic conditions of the syllables of which they are components. At a moderate tempo, consonants in syllable-final position combine with the onset consonant of the following syllable. This affects durational characteristics and may be explained by higher energy efficiency of CV units in production. Phonological phenomena are related to the shifts in syllable position and the temporal compensations of intervocalic consonant production. Studies of consonant perception in fluent context have dealt with tempo of utterance, position in word, and rhythmic pattern, as well as phonemic context. Major phenomena are effects of coarticulation, invariance in consonant perception, and cue interaction and masking. Much evidence suggests a dominance of the perceptual cues in the CV portion of VCCV and VCV sequences. We suggest that exploration of perception variables that affect consonants in fluent context would be expedited by reorienting experimental procedures to employ listener adjustment of stimuli, instead of the traditional phoneme identification and discrimination procedures with large sets of constant stimuli. Most of the relevant literature deals with stop consonants. Lateral, rhotic, and nasal consonants also deserve intensive study because of their very frequent occurrence. Theoretical issues of phoneme perceptual invariance and motor vs. auditory theory of perception are discussed in relation to proposed experiments which vary syllable tempo and stress pattern.