Abstract: A plurality of speech channels uses only one speech analyzer-synthesizer by Time-Multiplexing-Demultiplexing (sampling and processing) the speech channels sequentially. On the transmission side, speech signals of a plurality of channels are multiplexed by a pulse code modulation system, a partial autocorrelation coefficient and an excitation signal which constitute a feature parameter of the speech are extracted from the multiplexed signals by means of a speech analyzer for respective digital outputs corresponding to respective speech signals, and the extracted feature parameter is multiplexed again and then transmitted to the receiving side. On the receiving side, the received multiplexed signal of the feature parameter is applied to a speech synthesizer on a time division basis for reproducing a multiplex pulse code modulation signal of the speech wave, and the reproduced signal is distributed among respective channels.