Transform Coding of Speech Using a Weighted
Vector Quantizer · 1988
A new medium-band speech coder is proposed which em- ploys a weighted vector quantization scheme in the transformed do- main. In this coding, linear prediction residue is transformed and vec- tor quantized. In order to control the quantization errors in the transformed domain, adaptively weighted matching is employed in- stead of conventional adaptive bit allocation. Therefore, the residual signal can be reconstructed by the decoder, even if the spectral enve- lope parameters are destroyed due to transmission errors. This coder is also capable of maintaining higher SNR performance than time do- main vector quantization coders for a wide range of computation com- plexities and for a wide range of bit rates. Coded speech is natural and unaffected by background noise. The mean opinion score for this coder at 7.2 kbit/s is comparable to that of 5.5-bit log PCM coded speech sampled at 6.4 kHz.