การแปรของค่าระยะเวลาของสระภาษาไทยในพยางค์ตาย DURATIONAL VARIATIONS OF THAI VOWELS IN CHECKED SYLLABLES

Abstract

This study investigates durational variation patterns of Thai vowels, especially segmental durations of a checked syllable which ends with final stop consonant, or with final glottal stop. Segmental durations of long monophthongs and diphthongs with no finals are also investigated for comparison. There are 23 target words produced by 6 Thai male participants. The participants were asked to read carrier sentences embedded with the target words. The data were analyzed using Praat program and statistical test.The results show that durations ranking from longest to shortest are as follows: long monophthong without final (VV) 234.20 msec, diphthong without final (VD) 225.27 msec, diphthong with final glottal stop (VDG) 218.67 msec, long monophthong with final stop (VVS) 168.20 msec, diphthong with final stop (VDS) 153.89 msec, short monophthong with final glottal stop (VG) 123.93 msec, short monophthong with final stop (VS) 86.56 msec. Therefore, when a vowel (any type) is followed by a glottal stop, the syllable becomes longer than when it is followed by an oral stop. That is to say, duration of VG is longer than that of VS. Likewise, duration of VDG is longer than that of VDS. Besides, results from one-way ANOVA post-hoc comparison test show the significant differences among the vowels of 7 types, specifically significant durational differences between VG and VS and that of VDG and VDS. Keywords : duration, vowel, stops, glottal stop, Thai