PURPOSE: To perform high compression of audio signal, by providing the means quantizing the analysis parameter corresponding to voice and silence from the result of discrimination of voice and silence for audio signal, and decoding the quantized parameter corresponding to voice and silence.

CONSTITUTION: The audio signal is fed to the voice/silence discriminator 103 and the analyser 106 from the input terminal 111 of the analysis side 102, the discriminator 105 discriminates the voice and silence of audio, and analyser 106 analyzes the audio with the analysis parameter, and coder 107 performs coding corresponding to the result of discrimination of voice and audio at the coder 107. Further, each parameter coded is fed to the decoder 108 at the synthesis side 103 through the quantized parameter delivery line, and each parameter quantized is decoded and each parameter and the silence/voice discriminated signal are fed to the syntheszer 109. The synthesizer 109 synthesizes each parameter decoded corresponding to voice/silence discrimination signal, and synthesized signal is outputted to the waveform output terminal 110.