Background noise suppression for speech enhancement and coding

A background noise suppression system developed by Motorola is included as a feature in IS-127, the TIA/EIA standard for the enhanced variable rate codec (EVRC) to be used in CDMA based telephone systems. We describe the algorithm used in this system and its implementation. We then present subjective listening test results showing the advantages of using such a system as a prefilter to a speech coder.