| 摘要 |
PURPOSE: To reduce the degree of discontinuity in each frame and to improve sound quality by executing pulse search for the multi-pulse encoding of a sound signal surely also in the latter half of each frame. CONSTITUTION: A mutual correlation function calculator 5 finds mutual correlation RHX between a sound signal XW and an weighted impulse response HW, and an autocorrelation function calculator 6 finds the autocorrelation RHH of the response HW. The mutual correlation RHX and the autocorrelation RHH are supplied to a pulse searcher 7 to search a pulse. The position and amplitude of the pulse found out by pulse search are supplied to an encoder 8, which encodes a linear predictive coefficientα, a pitch P, a pitch predictive coefficientβ, and the position and amplitude of the pulse and transmits the encoded results to a transmission line 11. In the case of predicting a pitch, the prescribed number of pulses counter from the start pulse out of the number of pulses per frame is applied to the pulse searching range of the whole frame and the pulse searching range of remaining pulses is limited only to the latter half of the frame. Consequently discontinuity in each frame is not generated and sound quanlity can be improved.
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