This read-write TruthValue controls whether background noise (comfort noise) is played to fill silence gaps when Voice Activity Detection is active on the interface, and it defaults to enabled. Administrators toggle it to control caller perception during VAD-induced silence, since fully silent gaps can sound like a dropped call to the listener even though VAD is working correctly. For example, disabling this on an interface might be done to save minimal bandwidth, but doing so risks callers thinking the line went dead during quiet periods.