Robust LPC parameter estimation in standard CELP 4800 bit/s speech coder

In order to decrease LPC spectral degradation in the USA FED STD 1016 4.8 kbit/s CELP speech coder, application of a robust LPC parameter estimation is proposed. Robust LPC methods, based on Huber´s M-estimation theory and a heuristic sample-selective two-stage robust procedure, are considered. Comparative experimental analysis is carried out based on the cepstral distance, as an objective spectral measure. Presented experimental analyses justify the use of the robust LPC methods in the standard CELP 4800 bit/s speech coder, showing that the best results are obtained by using the combined sample-selective robust LPC procedure