Wavelet linear prediction vocoder based on auditory model

It is very difficult but very important to get higher quantity at lower bit rate in the field of speech coding. Traditional vocoders, such as LPC10e and CELPC, can give acceptable results but suffer from a hoarse output. We attribute this problem to the inconsistency between the equal resolution characteristic of linear prediction throughout the whole frequency band and the characteristic of the human ear´s unequal resolution at different frequency bands. In this paper, we present a new wavelet linear prediction subband coding algorithm (WLPSC), by employing a wavelet filter bank based on the auditory model. We divide the input speech signal into four subbands, and then code each subband respectively. Experimental results show that this algorithm can greatly reduce the hoarse output of vocoders