The effects of vowel length and place of articulation of the following stop on formant frequencies in Thai vowels

This study examined the effects of vowel length and place of articulation of the following stop on duration and formant frequencies in Thai vowels. Vowel length is phonemically contrastive in Thai as in languages such as Japanese. In a recent study on Japanese vowels, there was a significant effect of vowel length on vowel quality such that long vowels generally occupied a more peripheral portion of the vowel space than did the short vowels [6]. We sought to determine if the same pattern could also be observed in Thai. Another phonetic variable known to affect vowel quality is the place of articulation of the following consonant [8]. In English, F1 displacement due to this factor is quite small whereas F2 is substantially displaced in the context of alveolar consonants. Twenty-two native speakers of Thai (5 male, 17 female) living in Sydney, Australia, participated in this study. CVC words (where the 2nd C is /p t k/) containing /a / or /a:/ written in Thai scripts were read three times in isolation in randomized orders. The EMU speech database system was used for marking the onset/offset of the speech segments of interest. The first two formant center frequencies (F1, F2) of the targe