Coarticulation and prosodic hierarchy

This paper attempts to discuss the relationship between segmental coarticulation and prosodic structure in Mandarin Chinese. The discussion is mainly based on the EPG measurements to a set of phrases and short sentences produced in moderate speed. Main parameters measured in this study include (1) inter-gesture timing: temporal intervals overlapped between different articulatory gestures of V1#C2 at prosodic boundaries with different strength. (2) articulatory integrality: linguo-palatal contact state of different articulatory gestures for the related segments. The preliminary EPG evidences obtained from this study show that, all the pre-boundary vowels (V1) at PW level strongly coarticulate with post-boundary consonants (C2); while there are less cross-boundary coarticulation between V1 and C2 at PP and IP levels; especially in IP level, the pre-boundary vowels are almost not interfered from the post-boundary consonants. These evidences suggest a close link between segmental articulation and prosodic control in speech production. The results of data analysis show that there exist a negative correlativity between the extent of coarticulation and the height of prosodic hierarchy, it offers an account of that the higher the prosodic level, the less the cross-boundary segmental overlapping, and the more sufficient segmental articulation. These evidences indicate that segmental coarticulation and suprsegmental (prosodic) organization is originally indivisible in speech production. Therefore, in modeling of articulatory planning of speech production, one must take account of the close link between prosodic structure and segmental phonetic manifestation.