Improving perceptual coding of narrowband audio signals at low rates

This paper discusses perceptual coding of narrowband audio signals at low rates. In particular, it proposes a new error measure which shapes the noise inside the critical bands, a window switching criterion based on the temporal masking effect of the hearing system, a more accurate model of the simultaneous masking effect of the hearing system, perceptually-based bit allocation algorithms based on two different approaches towards quantization noise shaping and a predictive vector quantization scheme to code the scale factors. The resulting coding scheme outperforms existing low rate speech coders for non-speech signals