1.6 kbit/s LP vocoder using time envelope
I.A. Atkinson, Ahmet M. KONDOZ, B.G. Evans · Electronics Letters · 1995
The authors present a linear prediction (LP) based vocoder in which speech waveforms are considered as having a time envelope, the shape of which contains important perceptual information. By ensuring that the time envelope of the synthetic speech closely matches that of the original, natural sounding synthetic speech can be achieved at 1.6 kbit/s.