Tree coding combined with TDHS for speech coding at 6.4 and 4.8 kbps

Abstract

Tree coding is combined with time domain harmonic scaling (TDHS) for speech coding at 6.4 and 4.8 kbps. In order to improve the robustness to channel errors, new pitch predictor, short-term predictor adaptation and gain adaptation methods are proposed for tree coder. New code trees with appropriate gain adaptation rules, new backward adaptive pitch predictor and robust short-term predictor adaptation algorithms are evaluated for both ideal and noisy channels. Paired comparison listening tests show that the 6.4 kbps coder (2-to-1 TDHS/2 bits/samples tree coding) has speech quality equivalent to 6 bit log-PCM at a sampling rate of 6400 samples/s.