| 摘要 |
PURPOSE: To adjust pulse width with a small operation quantity and obtain superior encoded sound quality by correcting the level of the pulse having the maximum absolute value of an evaluation function among positions where pulses that are already found rise. CONSTITUTION: A pulse search circuit 5 uses cross correlation found by a cross correlation arithmetic circuit 3 as a 2nd arithmetic means as an evaluation function and each time one of multipulses is newly determined, the level of the pulse at the time position where the absolute value of the evaluation function becomes maximum among the pulses that are already determined is corrected. A value normalized to the level of correction of the pulse at the time position is subtracted from the value of the cross correlation at the time position where the absolute value of the evaluation function found by an autocorrelation arithmetic circuit 4 as a 3rd arithmetic means from the said evaluation function becomes maximum to find a new evaluation function. Further, a pulse following the newly determined pulse at the time position where the absolute value of the new evaluation function becomes maximum is determined. Consequently, the quality of an encoded speech can be improved with a small arithmetic quantity. |
