64‐kb/s wideband speech coding algorithm based on bandsplitting and adaptive prediction
Junji Suzuki, Masahiro Taka · Electronics and Communications in Japan (Part I Communications) · 1986
Abstract The wideband speech signal spectrum is mainly distributed within the low‐frequency band. Subband coding and adaptive predictive coding have been proposed as low‐bit rate speech coding algorithms to take advantage of this property. This paper theoretically clarifies the improvement in signal‐to‐quantization noise ratio when these two bit‐rate reduction techniques are used at the same time and quantitatively analyzes the speech signal spectrum distribution. It also proposes a wideband speech coding algorithm which encodes 7‐kHz‐band speech signals at 64 kb/s, the same encoding bit rate as that of the conventional companding PCM. Through computer simulation the subjective quality is evaluated and the effectiveness of the algorithm is shown.