| 摘要 |
PURPOSE:To correctly measure zero-cross intervals of an input waveform corresponding to one pitch cycle by eliminating the influence of zero crossing of an overtone component when a pitch is extracted from voice signal of a human voice, a musical sound, etc. CONSTITUTION:A CPU measures the maximum values of the interval between zero-cross points at both ends of a waveform part (a) whose polarity is, for example, positive and the amplitude of the waveform part (a) and then measures the maximum values of respective intervals between zero-cross points at both ends of respective waveform parts (b), (c), and (d) having the same polarity and the amplitudes of the waveform parts in order. Then when the waveform part (d) where the maximum values of both the internal and amplitude are nearly equal to the maximum values of the interval and amplitude of the waveform part (a) and which is at the shortest distance in terms of time is found, the interval between the start points (zero-cross point) of the waveform parts (a) and (d) is extracted as the pitch cycle of the input waveform. Then the above mentioned serial process are repeated thereafter. |
