Relationship between Vowel Quality and Vowel Space Size in Southeast Asian Languages

Abstract

Vowel space is a boundary of resonant frequency in Acoustics Phonetics, which is a formant frequency that explains vowel quality. The r elationship between vowel quality and a vowel space size has been investigated by many researchers, but no one has described the relationship clearly.

The aims of the present work are to study and to compare the relationship between vowel quality and a vowel space size. The researcher hypothesized that vowel qualities (i.e. vowel length quality, oral-nasal quality, and register quality) were not related to a vowel space size.

The methods of this study were to investigate monophthongs of the five Southeast Asian languages (i.e. Pwo Karen, Saek, Mpi, Lamet, and Bru). The participants of the study were 15 males (3 males for each language). Praat program was used for recording sounds and analyzing acoustic data. Word lists were created based on the vowel inventory of each language. The five test tokens of each vowel were selected for acoustic analysis. The acoustic measurement of vowel focused on the first formant frequency (F1) and the second formant frequency (F2). The measurement value in Hertz of the formant frequencies was normalized by reducing the difference among speakers with the S-centroid vowel normalization. The vowel space size was calculated using the polygon space formula.

The results of study showed the relationship between vowel quality and a vowel space size in three main points. T he first point was that the vowel length quality did not correspond with the vowel space size, which did not support the hypothesis. As we can see, that the long vowel in Bru has larger vowel space size than the short vowel. The second point was that the oral-nasal quality did not correspond with the vowel space size. This supported the hypothesis in that oral vowels in some languages have a smaller vowel
space size than their nasal vowels, while oral vowels in some languages have a larger vowel space size than their nasal vowels. The third point was that the register quality did not correspond with the vowel space si ze, which supported the hypothesis. It could be noticed that modal-voiced vowels in some languages have both larger and smaller vowel space sizes than their creaky-voiced vowels. Likewise, modal-voiced vowels in some languages have both larger and smaller vowel space sizes than their breathy-voiced vowels.