| 摘要 |
PURPOSE:To improve the sound quality by discriminating the voice/silence of an input voice so as to vary the number of drive sound source pulses and the number of quantized bits of a sound source pulse, thereby improving the reproducibility of a waveform at the silent part. CONSTITUTION:An input voice signal is inputted to a voice/silence discrimination section 2 and a sound source pulse retrieval section 3. Tables 4, 5 of the number of sound source pulses to be obtained corresponding to the result of voice/silence discrimination are selected, its result is fed to the retrieval section 3 through a switch 6, the number of sound source pulses designated by the input voice is extracted and fed to a quantizer 8 or 9 through a switch 7. Switches 7, 10 select the quantizer 8 or 9 corresponding to the result of voice/silence. The result of quantization is multiplexed together with the discrimination result of voice/silence and sent to a decoder. The decoder side discriminates (11) the voice/silence to select a number of sound source pulses table 12 or 13, the number of sound source pulses designated from a reception data is decoded (15), subject to inverse quantization (17, 18) to introduce the sound source pulse. |
