1960 年 16 巻 4 号 p. 289-291
Measurements were given on the time variation of fundamental frequencies of speech sounds of five Japanese isolated vowels spoken by two males and two females. This characteristic seemed to be one of the important factors having an affect on the naturalness of speech sounds. From the measurements and the analysis of data, it is found that the patterns of the variation have always convex forms, that the upward going parts of the patterns have not significant difference among speakers, and that the variation has the characteristics of having remarkable various patterns in the conditions of speaking especially in speaking effort. The spectra of measured curves were determined. Suppose that the mean fundamental frequency is frequency-modulated with the components of above spectra, the spectra of this F. M. wave and the bandwidth covering the 99% of the total spectrum energy are able to be computed. The spectrum envelope may be approximated to have the normal distribution curve, and the bandwidth is found to be strongly correlated to the mean fundamental frequency, and its values are determined to have 20 c/s-50 c/s with male voice and 60 c/s-90 c/s with female one.