Effects of Noises on Fundamental Frequency Extraction Using Cepstral Analysis for Thai Dialects

Problem statement: The fundamental frequency (F0) of the human speech corresponds to the vibration frequency of the human vocal chords. To extract the F0 from a speech utterance, one approach is based on the Cepstral analysis. In Thai, there are four main dialects spoken by Thai people residing in four core region including central, north, northeast and south regions. Environmental noises are also playing an important role in corrupting the speech quality. It is needed to study of effects of noises on F0 extraction using the Cepstral analysis for Thai dialects. Approach: The Cepstral analysis is performed and some coefficients are used to determine the corresponding F0 values. Four types of environmental noises are simulated with different levels of power. The differences among the extracted F0 from clean speech and the extracted F0 from noise-corrupted speech are calculated in Root Mean Square (RMS) errors. Results: The selected noises are train, factory, car and air conditioner. Five levels of each type of noise vary from 0-20 dB. From the experimental results, it has been noticed that the effects of noises are different. The lowest effect is of air conditioner, meanwhile the noise level of 0 dB is of the highest effect. Conclusion: By using the Cepstral analysis, F0 values can be extracted from the noise-corrupted speech with different level of effects depending on the type and level of noises.