Timing and coordination in tone and intonation

Timing is of critical importance for speech in general and for tone and intonation in particular. Yet our understanding of timing is still limited. In this paper I explore timing related issues from an articulatory-functional perspective, which views speech as communicative functions encoded through an articulation process. Based on this view, timing in speech can be seen as of two kinds, obligatory timing — timing as obligated by articulation, and informational timing — timing that encodes communicative meanings. I will show that the articulatory constraints of minimal movement duration and syllable-bound temporal alignment severely limit the freedom of using timing for information coding, leaving duration as the only controllable aspect of timing. I will further show that duration, as other aspects of speech, is used to encode multiple layers of communicative meanings in parallel, allowing concurrent encoding of lexical contrast, focus, and inter-constituent affinity. Such information coding seems to account for previously reported duration patterns such as polysyllabic shortening and constituent-edge lengthening. Furthermore, to the extent the reported weak isochrony tendency can be explained by information coding and articulatory mechanisms that have little to do with isochrony, speech rhythm seems to be an epiphenomenon rather than a basic mechanism.