Effect of speech rate on inter-segmental coarticulation in Standard Chinese

Coarticulatory variations of consonant clusters spanning morpheme boundary and transconsonantal vocalic articulatory transition in Standard Chinese as a function of speech rates were investigated. Eight /V1C1#C2V2/ and eight /V1#pV2/ disyllable sequences were uttered by a female speaker at slow, normal, and fast speech rate. Electropalatographic, electroglottographic, and acoustic data were recorded and the kinematic properties of segments and the inter-segmental temporal coarticulation were analyzed. Results showed articulatory duration shortening and increased temporal coarticulation were the two major motor control mechanisms involved in fast speech. Consonant production manner, coupling effect of tongue body movement in consonant production, and prosodic affiliation of vowels were found to affect kinematic properties of segments and inter-segmental coarticulation when speech rate is increased. In the acoustic domain, the F2 trajectory was found to be sensitive to the increased gestural overlapping in fast speech. However, the correlation between the linguapalatal contact in mid-portion of vowels and the relative same-time F2 values was vague. It was also found that inter-segmental coarticulation was independent of the suprasegmental tier, which tends to speak against the tenets of the time structure model.