Structural Modeling of Fundamental Frequency Contour for Thai Expressive Speech

Problem statement: Appropriate modeling of fundamental Frequency (F₀) contour for speech is a key factor to preserve the quality of speech prosody. One successful approach has been conducted for tonal language of Mandarin Chinese. It is based on the assumption that the behavioral characteristics of vocal-fold elongation in vibration could be approximated by those of a simple forced vibrating system. Therefore this approach has been applied to model Thai expressive speech with best-fit function. Approach: An approach of structural modeling of voice F₀ contours of Thai expressive speech utterances using an approximation by those of a simple forced vibrating system has been conducted. Nowadays, modeling of F₀ contours of Thai expressive speech is very important in an analysis of speech, which brings about the speech communication with more interesting and effective. Our speech database consists of male and female speech and each one contains 4 different speech styles including angry style, sad style and enjoyable style and reading style. We use 5 sentences for each speech style and each sentence includes 100 samples. The speech sample in each group is analyzed for an F₀ contour, subsequently a number of structural modeling parameters are extracted for each contour. Thereafter, the parameters are used to synthesis the F₀ contour and then the synthesized contour is compared with that of natural speech by calculating RMS error. Results: From the experimental analysis, it is observed that RMS error of each speech style is different from the others. It reveals that the mentioned structural modeling responses to each speech style differently. Moreover the reading style has the smallest error among all styles. Conclusion: From the finding, it is a definite evidence to apply the modeling approach to the speech synthesis systems with good preservation of speech prosody.