A new medium-band speech coder is proposed which employs a weighted vector quantization scheme in the transformed domain. In this coding, linear prediction residue is transformed and vector quantized. In order to control the quantization errors in the transformed domain, adaptively weighted matching is employed instead of 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. This coder is also capable of maintaining higher SNR performance than time domain vector quantization coders for a wide range of computation complexities 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.
ASJC Scopus subject areas
- コンピュータ ネットワークおよび通信