Hybrid frequency-domain coding of speech signals

A new method of speech coding called hybrid frequency-domain coding is introduced and its application to speech transmission at bit rates of 7.2 and 9.6 kbit/s is studied. The hybrid frequency-domain coding system is based on a combination of sub-band coding and transform coding techniques. Subjective tests have shown that the quality of speech produced by the hybrid frequency-domain technique at 7.2 kbit/s is comparable with 19 kbit/s continuously variable slope delta modulation (CVSD), and that at 9.6 kbit/s, it is comparable with 23 kbit/s CVSD.