| 摘要 |
PROBLEM TO BE SOLVED: To accurately find a pitch cycle fast with inexpensive constitution even when a speech waveform is a complicated waveform containing an overtone component. SOLUTION: A digital speech signal is oversampled by four-times oversampling 7 and the result is binarized by a binarization part 8; and inversion intervals of the signal obtained by the binarization are measured by a timer 9 to find successive zero-crossing intervals of the digital speech signal, and the intervals are stored in a RAM 10. A pitch arithmetic part 11 assumes that the pitch cycle is the sum of 2n pieces of zero-crossing interval data as to n=1-4, calculates a reproduction rate as the degree of matching in each pitch cycle of each zero-crossing interval data constituting one pitch cycle, and employs the assumption by which the highest reproduction rate is obtained to find the pitch cycle. |
