| 摘要 |
PURPOSE:To transmit sound source information with higher accuracy by releasing the number of bits which have been allocated to spectral information, to the sound source information. CONSTITUTION:As for an input voice of a terminal 1, a spectrum coefficient of n-order is derived by a spectrum extractor 2, and said voice is inputted to a register 3 and one terminal of a difference circuit 4. An output of the register and the other terminal of the difference circuit 4 are connected to one contact of a switch 7. An output of a threshold value generator 5 and an output of the difference circuit 4 are inputted to a comparing circuit 6. Subsequently, a pulse search 9 is executed by switching the switches 7, 12 and a quantization table 8 by an output of the comparing circuit and the pulse is outputted to a multiplexing circuit 10. The circuit 10 multiplexes and sends out spectral information, etc., which are obtained through the switch 12. When an absolute value difference of the spectral information of the past and the present analysis frames is smaller than a threshold value, the number of information allocating bits is applied to sound source information by using the past information, the spectral information used for a synthesizing filter is changed to the past information, the number of allocating bits of the sound source information is changed, the information is increased by a vowel stationary part, etc., and the tone quality is improved. |
