Enhancing Speech Coder Quality: Improved Noise Estimation for Postlters
Cheick Mohamed Konat · 2011
ITU-T G.711.1 is a multirate wideband extension for the well-known ITU-T G.711 pulse code modulation of voice frequencies. The extended system is fully interoperable with the legacy narrowband one. In the case where the legacy G.711 is used to code a speech signal and G.711.1 is used to decode it, quantization noise may be audible. For this situation, the standard proposes an optional postfilter. The application of postfiltering requires an estimation of the quantization noise. The more accurate the estimate of the quantization noise is, the better the performance of the postfilter can be. In this thesis, we propose an improved noise estimator for the postfilter proposed for the G.711.1 codec and assess its performance. The proposed estimator provides a more accurate estimate of the noise with the same computational complexity.