Critical point coding: Design and real-time implementation at 16 kbps

This paper discusses the effort to develop and implement a high quality speech coding algorithm for transmission over a 16 kbps communications channel. The goal of this work was to achieve higher speech quality and intelligibility than that obtained by Continuously Variable Slope Delta-Modulation (CVSD), the current DOD mediumband standard algorithm. Our speech system, uses as a preprocessor, Time Domain Harmonic Scaling (TDHS), developed by David Malah of Bell Laboratories, with Critical Point Coding (CPC), a new waveform coding technique developed at MITRE. The result is a speech coding system running in real-time on a MAP-300 array processor which produces high quality speech at 16 kbps.