Syllable-based Pitch Encoding for Low Bit Rate Speech Coding with Recognition/Synthesis Architecture

Current HMM-based low bit rate speech coding systems work with phonetic vocoders. Pitch contour coding (on frame or phoneme level) is usually fairly orthogonal to other speech coding parameters. We make an assumption in our work that the speech signal contains supra-segmental cues. Hence, we present encoding of the pitch on the syllable level, used in the framework of a recognition/synthesis speech coder with phonetic vocoder. The results imply that high accuracy pitch contour reconstruction with negligible speech quality degradation is possible. The proposed pitch encoding technique operates on 30 - 35 bits per second.