EUROSPEECH '97

The quantization of linear prediction coefficients (LPC) is an important aspect in low bit rate speech coding. In this work, we introduce a new approach, which exploits the temporal dependencies in the line spectral frequencies (LSF). We approximate each LSF track using expansion into wavelet basis functions. As the LSF vary fairly smoothly as functions of time, they perform very well when interpolated. By vector quantizing the resulting wavelet expansion coefficients, the interpolated LSF tracks could be quantized with a distortion of 0.91 dB using only 15.6 bits per 20 ms update (780 bits per second). This is about 4 bits per update less than the results obtained with previously described procedures.
Bibliographic reference. Lemma, Aweke N. / Kleijn, W. Bastiaan / Deprettere, Ed F. (1997): "Quantization using wavelet based temporal decomposition of the LSF", In EUROSPEECH1997, 12591262.