TRANSFORM CODING OF SPEECH WITH WEIGHTED VECTOR QUANTIZATION.

A transform coding of speech that uses a weighted vector quantization scheme is propopsed. First, the characteristics of the weighted vector quantization are checked. Then based on these considerations, a frequency-domain coder is designed for medium-band (4. 8-9. 6 kb/s) speech coding. In this coding scheme, the linear prediction residue is transformed and vector-quantized. In order to control the quantization errors in the frequency domain, adaptively weighted matching is used instead of the conventional adaptive bit allocation. Therefore, the residual signal can be reconstructed by the decoder, even if the spectral envelope parameters are destroyed due to transmission errors. The coded speech is natural and unaffected by background noise and its mean opinion score at 7. 2 kb/ps is comparable to that of 5. 5-b log PCM-coded speech.