Low bit rate speech coding at 1.2 and 2.4 kb/s

摘要

At 4.8 kb/s and below, conventional code excited linear prediction (CELP) does not provide the appropriate degree of periodicity. It has been suggested that good quality low bit rate speech can be obtained from frequency domain techniques. A MB-LPC vocoder operating at 2.4 and 1.2 kb/s exploits the advantages of both time and frequency domain speech coding to product natural sounding, good quality speech. This includes a new frequency domain post-filter which attenuates the noise in the formant nulls and enhances the synthesized speech.