Spectral envelope quantization with noise robustness

To represent the spectral envelope, the LSF (line spectrum frequencies) can be used for its good properties in quantization. The interframe correlation of the LSF improves the performance of static quantization, but it is sensitive to channel errors. The proposed quantizer, noise robust-switched prediction-linked split vector quantizer (NR-SP-LSVQ), combines switched prediction with three static and a predictive quantizers. It limits the propagation of channel errors in a few frames by switching to the static ones. Moreover, each of the static ones is designed for the robustness against background noise, while the predictive one is for the steady region of speech. It increases the performance in noise corrupted as well as clean speech