Digital speech networks

A program report is presented on digital voice terminals which accept the acoustic speech signal and translate it into a digital bit stream. Progress in the development of speech algorithms, combined with great advances in digital technology and the digital signal processing techniques, have reduced terminal size and cost and increased reliability to a point where a widespread use of such devices can be predicted. An investigation is conducted concerning the characteristics of speech considered as data. Speech analysis-synthesis systems are discussed, taking into account channel vocoders, linear predictive coding (LPC) vocoders, the coding of LPC parameters, a homomorphic vocoder, the estimation of fundamental frequency and the voicing decision, speech coding using predictive methods, and the adaptive predictive coding of speech. The implementation of speech processing algorithms is considered and a description is given of packet speech experiments.