LOW BIT-RATE SPEECH CODING BY PERCEPTUALLY OPTIMIZED NOISE EXCITATIONMODULATION

A novel low bit-rate high-quality speech coding technique is presented based on a perceptually optimized signal reconstruction method. Accor ding to this parametric speech model, the signal's spectral envelope i s reconstructed from non-linear spectral filtering of an excitation si gnal, which is a combination of a random broadband noise signal with a number of discrete spectral pulses extracted from the original speech using a perceptual model. This general coding platform allows variabl e bit-rate implementations, starting from 1.9 kbit/s, at which suffici ent intelligibility (more than 92%) was measured, while at higher bit- rates (2.8 kbit/s) intelligibility scores were better than 94% with su fficient naturalness in the coded speech. In all cases, the complexity of the proposed system is very low. (C) 1997 Elsevier Science B.V.