Are syllables units of speech motor organization? A kinematic analysis of labial and velar gestures in Cantonese

Syllable level organization has been observed in articulatory movement patterns in American English (Krakow, 1989; Sproat & Fujimura, 1993; Browman & Goldstein, 1994). This study investigates the issue of universality of syllable structure from the aspect of articulatory phonetics. Articulatory characteristics and coordination patterns of two independent articulatory subsystems, velum and lower lip, and their acoustic manifestations, are examined during the production of Cantonese disyllabic nonsense utterances containing /m/ in one of three syllable positions, syllable-initial, syllable-final or syllabic. The results indicate consistent effects of syllable structure on both velar and lower lip movements, spatially and temporally, for the utterances examined. For utterances containing syllabic nasals, compared to those with syllable-final or syllable-initial nasals, durations of velar lowering and the low velar plateau were longer, displacement amplitudes of velar lowering were greater, and the positional minimum of the velum was lower; similarly, greater durations and displacement amplitudes of lower-lip gestures were also found for utterances with syllabic nasals. For utterances with syllable-final nasals, compared to those with syllable-initial nasals, greater displacement amplitudes of velar lowering, lower positional minima of the velum and longer durations of lower-lip plateau were found. Acoustic duration of nasal murmur also showed clear differences. Effects of syllable structure were also found on the coordination patterns between the velar and lower lip movement. For utterances with syllabic nasals, compared to those with syllable-final or syllable-initial nasals, velar movement began earlier and finished later relative to lower lip movement. In utterances with syllable-final nasals, although the downward velar movement began no later than those with syllable-initial nasals, the velum reached a relatively lower position than in those with initial nasals.^ Comparisons of these findings to those for American English (Krakow, 1989) indicate that, while in both languages, articulatory movement patterns of velum and lower-lip systematically show evidence of syllable level organization, the actual patterning is quite different between the two. A syllable structure patterning model is proposed to account for the differences.