The articulatory tone-bearing unit: Gestural coordination of lexical tone in Thai

Abstract

Recently, tones have been analyzed as articulatory gestures that can coordinate with segmental gestures. In this paper, we show that the tone gestures that make up a HL contour tone are differentially coordinated with articulatory gestures in Thai syllables, and that the coordinative patterns are influenced by the segments and moraic structure of the syllables. The autosegmental approach to lexical tone describes tone as a suprasegment that must be associated to some tone-bearing unit (TBU); in Thai, the language of study, the proposed TBU is the mora. Although the autosegmental account largely describes the phonological patterning of tones, it remains unclear how the abstract representation of tone is implemented. An electromagnetic articulograph (EMA) study of four speakers of Thai was conducted to examine the effects of segment type and moraic structure on the coordination of tone gestures. In a HL contour tone, tone gestures behave similarly to consonant gestures, and show patterns of coordination with gestures that correspond to moraic segments. However, there is also a level of coordination between the H and L tone gestures. Based on these results, a model of TBUs is proposed within the Articulatory Phonology framework that incorporates tone-segment coordination as well as tone-tone coordination.