| 摘要 |
PURPOSE:To offer the multi-pulse type voice encoding and decoding device which can be improved in voice quality by determining the best number of pulses by using a difference of cross-correlation coefficient electric power. CONSTITUTION:An auditorily weighted waveform calculator 7 calculates an auditorily weighted waveform by using an alpha parameter, an attenuation alpha parame ter, and an input voice waveform. A cross-correlation coefficient calculator 8 calculates the cross-correlation coefficients of an impulse response waveform and the auditorily weighted waveform. A multi-pulse retrieval device 10 searches for the point where the absolute value of the cross-correlation coefficient is maximum and sets a pulse at the point. A cross-correlation coefficient electric power calculator 11 calculates the sum of the squares of the cross-correlation coefficient, i.e. cross-correlation coefficient electric power every time the pulse is set and the cross-correlation coefficient is corrected. A difference electric power calculator 12 calculates the difference between values of electric power found by the cross-correlation coefficient electric power calculator 11. A pulse number decision device 13 determines the best number of pulses according to the difference electric power. |
