Structural and functional aspects of tone split in Thai

Abstract

Comparative and diachronic work throughout this century has laid a very strong foundation for the hypothesis that Thai owes its great number of tones to processes which created tones and splitted existing tones at an earlier stage of the language, and the further hypothesis that those processes had a direct connection with consonant mutations which involved segmental loss of contrast. Since the sixties, studies of Thai tones have emphasize the phonetic aspects of tonogenesis or tone split (cf. the key-note paper of Abramson and Erickson 1991). It is argued in the present paper that although the hypotheses stated above are not at issue, the diachronic scenario is still poorly understood, both with respect to the underlying phonetic mechanisms and with respect to the structural and functional aspects of the sound changes. It is a stumbling-stone for the formulation of phonetic explanations of tone split that there are quite different types of consonants involved, and with quite different diachronic behaviour. The paper suggests that higher-level (cognitive-phonological) categorization of syllable types may have played a central role in the implementation of tone split. Another issue is the striking variation in tone systems across the whole gamut of Thai dialects. The paper takes issue with the general assumption that early Thai developed a grossly over-complex tone system which was subsequently drastically reduced, and that the dialectal variation essentially reflects alternative simplifications. It is argued in this paper that the tone splits which we can observe in the modern dialects, are individual and functionally optimal solutions to the preservation of contrast between syllable types. It is further argued that there is no compelling reason to project tone split back to a period which was prior to the breaking-up of Thai into its present main dialects. Tone split may have spread geographically across dialects at a later date, each dialect responding according to its specific structural properties.