PURPOSE:To improve an unpleasant sense of a reproduced voice in a auditory sensation caused by a difference of a level of pseudo noise from a background noise level at a sender side when the adaptive difference PCM system for the voice coding communication system. CONSTITUTION:A sender side encoder is provided with a C/N flag generator 3 and a changeover device 5, a C/N flag representing a non-voice block and a coded background noise are sent for a prescribed time only during the non- voice block and succeeding transmission is stopped. A receiver side decoder is provided with changeover devices 8, 11 and a C/N gain adjustment device 10, and when a C/N flag is detected, a prediction coefficient and a level at decoding of succeeding background noise are latched and the succeeding pseudo noise is decoded by using the latched prediction coefficient. Moreover, the level is corrected by the C/N gain adjustment device to obtain a reproduced output.
VOICE CODING COMMUNICATION SYSTEM AND EQUIPMENT THEREFOR