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 frequency-domain 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.