European Conference on Speech Technology

Edinburgh, Scotland, UK
September 1987

Hybrid Transform Coder for Low Bit Rate Speech Coding

A. Kondoz, B. G. Evans

Dept. of Electronic and Electrical Engineering, University of Surrey, Guildford, Surrey, UK

Frequency domain speech coding techniques such as sub-band coder (SBC) (ref 1) and adaptive transform, coder (ATC) (ref 2) can produce high quality digital speech at around 16 Kb/s. However, at bit rates below 16 Kb/s, their rapidly deteriorating speech quality and increasing complexity make them less competitive to the time domain coders such as residual excited linear prediction (RELP) (ref 3). In this study a hybrid of ideas from ATC, RELP, and vector quantization (VQ) are put together in order to improve the quality of a low bit rate transform coder. Informal listening tests have shown that the proposed coder out-performs the speech specific ATC (SSATC) (ref 2) at 9.6 Kb/s as well as SBC (ref 1) and RELP (ref 3).

Full Paper

Bibliographic reference.  Kondoz, A. / Evans, B. G. (1987): "Hybrid transform coder for low bit rate speech coding", In ECST-1987, 2105-2108.