Enhancing vocoder performance for music signals

Low bit rate standards involving the code excited linear predictive coder (CELP) are typically optimized for telephone speech. The performance of CELP with non-speech signals and particularly with music degrades considerably. It is of interest these days to improve the robustness of these coders by adding pre-and post-processing stages to the core compression algorithm. In this paper, we propose a frequencydomain technique involving time-varying filters to enhance the audio quality with a small number of overhead information bits. Preliminary results have shown both qualitative and quantitative improvements in the sound quality.