| 摘要 |
PROBLEM TO BE SOLVED: To accurately find a pitch cycle fast and accurately even when a speech waveform is a complicated waveform containing an overtone component or when a fine noise is superposed on the speech waveform. SOLUTION: A binarization part 8 which has a masking zone nearby the zero level converts a digital speech signal into a binary signal. Then, a timer 9 measures the inversion intervals of the binary signal to find successive zero- crossing intervals of the digital speech signal and stores them 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. |
