Analytical Study on Fundamental Frequency Contours of Thai Tones using Tone-Geometrical Model

Problem statement: In tonal language speech; such as Thai, Mandarin and Vietnam, tone is an important feature of a syllable that must be taken into consideration, since tone is a supra-segmental feature in the speech prosody. Modeling of tone with high accuracy could enhance the quality of synthesized speech in the speech synthesis system. This study focuses on a model analysis of fundamental frequency (F0) contours of Thai tones using tone-geometrical model. Approach: Tonegeometrical model applied is this study is a basic model which is expected to extract the dimensional features of a syllable-length portion of fundamental frequency contour. Seven selected parameters are extracted from a syllable-length portion of fundamental frequency contour and then are analyzed. Results: In the experiments, 2,500 speech utterances from TSynC-1 speech database were selected and used as speech materials. The distributions for all seven parameters are presented. The statistical figures of mean and standard deviation values from five tones are also calculated. The results show that most of the proposed parameters can distinguish five Thai tones explicitly. Conclusion: From the finding, the proposed parameters of tone-geometrical model could be further applied in the speech or other speech processing technologies.