A RESEARCH ON SPEECH QUALITY OF CHANNEL VOCODER
Iqing Mo · 声学学报(英文版) · 1986
2400 bit/s digital vocoder plays a very important role in narrow-band speech communication. This paper presents a channel vocoder designed by using multiple 8085 microprocessors and some special hardware. In order to improve the quality of synthesis speech of the vocoder, special attentions were paid to the improvement of excitation signals by using an all-pass filter, the composite response and group delay of the synthesis filter bank adjusted by change bandwidth of filters and with anti-polarity for adjacent filters, and the efficient method of encoding and decoding for Chinese speech parameters. The effect of all these methods has been verified in the results of intelligibility tests. This paper describes the results of intelligibility tests also.