A novel acoustic way of demarcating diphthong elements in Thai

Abstract

Thai has three phonemic (falling) diphthongs /ia/, /i‘a/, and /ua/ and a set of the so-called rising diphthongs in Thai /ai/ /aj/ and /au/ /aw/. In previous (nonacoustic) literature, falling diphthongs are short when followed by a glottal stop. However, recent acoustic studies revealed that falling diphthongs in Thai are short in closed syllables, but long in open syllables. In the same literature, each diphthong was measured for the durations of its first vocalic element, the transition, and the second vocalic element, without demarcating the offset of the first vocalic element and the onset of the second vocalic element. This paper has the major aim of applying a new technique for making a plausible way to mark where the first vocalic element ends and the second vocalic element starts, not only for the set of falling diphthongs but also for the so-called rising diphthongs. Moreover, this new technique would help to find out whether the rising diphthongs in Thai have the combinations of two-vowel qualities or a vowel and a glide. It is hoped that this new method will be useful for the future acoustic studies in other languages of the world. [Work supported by new-lecturer grants, Chulalongkorn University.]