| 摘要 |
PURPOSE:To extract a pitch with high accuracy, by adding the almost-period of the pitch calculated by counting the number of samples of digital data and the fraction pitch calculated by interpolating two or more data read from a memory part. CONSTITUTION:The acoustic signal passed through an HPF 1 and an LPF 2 is converted on the basis of the sampling frequency of Fs(Hz) as an acoustic signal limited in a band by an A/D converter 3 to be successively outputted to a polarity reversal detection part 4, a memory part 7 and control part 8. Next, when the detection part 4 detects the reversal of the polarity of successively inputted digital data, said detection part 4 sends out a clocking indication signal to a control part 8. This control part 8 begins to count the number of the samples of successively inputted digital data and reads two digital data reversed in polarity from the memory part 7 to calculate a zero cross point according to an interpolation system. Further, the control part 8 respectively adds a count value when counting is finished and subsequently resets the count value to zero and outputs the addition result as a pitch cycle. |
