Abstract:
This study aims at investigating f[subscript 0] behavior of vowels influenced by vowel quality, initial consonants, final consonants and surrounding consonants which share the same manner of articulation inthe 3 languages of the Waic branch of the Mon-Khmer language family, namely Wa (a registered language), Lavua' (a restructured language), and Plang (a tonal language). Six informants from each language were divided equally into 2 groups; those over 60 years of age and those below 20 below 20 years. They were asked to pronounce 60-70 words 3 times, a total of 3,546 tokens. The fundamental frequency value of all the tokens was recorded and analyses using Praat. Line graphs were drawn. Tonal realisations in different contexts were analysed statistically, using a t-test. The results are as follows: Vowel Quality: (1) high vowels have a higher f[subscript 0] than low vowels, and (2) breathy-voiced vowels have a lower f[subscript 0] than modal-voiced vowels in accordance with the hypothesis. Influence of initial consonants: (1) vowels which follow cluster consonants have a lower f[subscript 0] than those which follow single consonants; thus failing to confirm the hypothesis (2) vowels which follow aspirated stop consonants have a lower f[subscript 0] than those which follow unaspirated stop consonants; thus also failing to confirm the hypothesis (3) vowels which follow prenasalized stop consonants have a lower f[subscript 0] than those which follow stop consonants; confirming the hypothesis, but vowels which follow prenasalized fricative consonants have a higher f[subscript 0] than those which follow fricative consonants, which fails to confirm the hypothesis (4) vowels which follow voiceless nasal consonants have a higher f[subscript 0] than vowels which follow preglottalized nasal consonants and vowels which follow voiced nasal consonants in accordance with the hypothesis. Influence of final consonants: vowels preceded by glottal stop consonants have a higher f[subscript 0] than those preceded by fricative consonants and those preceded by nasal consonants, which does not conform with the hypothesis. Influence of surrounding consonants which share the same manner of articulation: vowels between voiceless stop consonants have a higher f[subscript 0] than those between fricative consonants and those between nasal consonants, which fail to confirm the hypothesis. Tones are created by the following influences: 1. Vowel Quality: breathy-voiced and modal-voiced vowels, 2. Initial consonants: (i) cluster and single consonants, (ii) aspirated and unaspirated consonants, (iii) prenasalized stop-stop consonants, and prenasalized fricative-fricative consonants, (iv) voiceless nasal-preglottalized nasal-voiced nasal, 3. final consonants, and 4. surrounding consonants which share the same manner of articulation. The study has found that the fundamental frequency of vowels in the context of initial consonants, final consonants, and surrounding consonants which share the same manner of articulation shows a universal tendency for voiceless consonants to raise the pitch, while voiced consonants will lower the pitch. The pitch contour of vowels preceding a glottal stop and a glottal fricative rises in Wa and Lavua' while in Plang it falls. The pitch contour of the older group is more dynamic than that of the younger one because the pitch height tends to give birth to the tone before the pitch contour does. The study has also found that the route of tonogenesis in Waic languages is as follows: it is plausible for Wa (register language) and Lavua' (restructured language) to become tonal languages, while Plang (tonal language) can develop more tones. Thus, tonal evolution process will not end only at the restructured stage or tonal stage, any types of non-tonal Waic languages can become tonal and the tonal ones will have more tones in the future