Transform representation of the spectra of acoustic speech segments with applications. II. Speech analysis, synthesis, and coding

For Part I see ibid., vol.1, no.2, p.180-95 (1993). In Part I of this paper, the authors introduced an approach to the representation of the speech spectral envelope which makes use of the Karhunen-Loeve (KL) transformation of acoustic subword segments. This signal-dependent representation captures, with a few KL vectors and transform coefficients, the perceptually and phonetically important structure of the spectral envelope. Here the authors apply this representation to the analysis, synthesis, and coding of speech. They propose simple quantization and coding strategies for the KL representation vectors as well as for the resulting transform coefficients. The resulting technique is a variable rate encoding scheme which achieves good speech quality at an average rate of 3.5 kb/s