Hideto Nakatsuji

Analysis of the sound of the Japanese voice using real-time spectral analysis

Voice signal processing requires real-time processing. For this reason, a new method which updates the spectrum by using input data is proposed. In this method, analysis in the time-frequency domain is executed as well as wavelet transform. Vowels /i/ and /e/ consist of fundamental, harmonic, and high frequency waves. These high frequency waves determine the sounds of /i/ and /e/. These high frequency waves may also exist in /a/ and /o/. In this article, we analyze these high frequency waves by using a new analyzing method, and we show the constitution of high frequency waves. Since the waveform of a consonant does not repeat, the analysis cannot be performed like the analysis of the high frequency wave of a vowel. In a consonant, we show the fluctuation of the spectrum with time.

Selection of parameters in the design of real-time spectral analysis

A new analytical method with high speed processing in the time-frequency domain is presented. In this method, sine and cosine waves with an established frequency and multiple periods are used, and we call these waves “cutting-out waves.” We all the frequency the “established frequency,” and we call the number of periods of the cutting-out wave the “number of periods.” The inner product of the cutting-out wave and the signal are calculated, and a signal element with a frequency near the established frequency is detected. We call the unit that detects the signal element an “auditory cell.” There are many auditory cells, and they have an established frequency which differs very little. The design of this method is the arrangement of the auditory cells. There are three parameters in the design, and these parameters are a sampling frequency, the number of periods, and the increasing rate of the established frequencies. In this article, we show the selection of these parameters.