On the Interaction between Tone and Vowel Length: Evidence from Thai Dialects

Abstract

Abstract The loss of a phonological distinction in vowel length historically among certain Thai dialects (spoken in Thailand) may be seen to be principally conditioned by tone. Available auditory, acoustic and other experimental data on the interaction between tone and vowel (syllable or tone-bearing unit) duration evidenced in several geographically and typologically distinct tone languages point to universal phonetic tendencies having to do with the production of tone. These phonetic tendencies are believed to have caused the changes in vowel duration thus bringing about a change in the phonological status of vowel length – a restructuring of the synchronic phonological systems among dialects and languages of the Tai language family. It is further suggested that the use of indivisible unit-contour tone features leads to an economic, explanatory diachronic and synchronic description of these phenomena.