Analysis of the self-excited subband coder: a new approach to medium band speech coding

A speech coding technique is introduced for bit rates below 10 kb/s. The coder exploits the frequency-domain properties of aural perception that are associated with subband coding and uses the block coding techniques which have recently been used to great advantage in low-rate full-band coders such as the self-excited vocoder and the code-excited linear predictive coder. The coder contains an analysis/synthesis system for decomposing the speech into contiguous frequency bands and merging the bands in reconstruction. The coding of the individual subbands is accomplished by using long-term predictors to represent channel outputs. Various configurations of the analysis/synthesis structure and the self-excitation model are considered. Issues related to the analysis procedure, the performance and the system efficiency are discussed