Comfort noise

[1] Some modern telephone systems (such as wireless and VoIP) use voice activity detection (VAD), a form of squelching where low volume levels are ignored by the transmitting device.In digital audio transmissions, this saves bandwidth of the communications channel by transmitting nothing when the source volume is under a certain threshold, leaving only louder sounds (such as the speaker's voice) to be sent.Although maximizing call quality is of primary importance, exhaustive removal of noise may not properly simulate the typical behavior of terminals on the PSTN system.This is to reassure the listener that the station is on-air, but primarily to prevent silence detection systems at transmitters from automatically starting backup tapes of music (designed to be broadcast in the case of transmission link failure).[5] A similar concept is that of sidetone, the effect of sound that is picked up by a telephone's mouthpiece and introduced (at low level) into the earpiece of the same handset, acting as feedback.
background noisewirelesssilencevoice activity detectionsquelchingvolumetransmittingdigital audiobandwidthsoundsDead airnoise gatereceivingRTP audio video profileRemembrance Sundaysiege of LeningradmetronomeLeningradradio networksidetoneAmbient noiseTalkspurtDiscontinuous transmissionPresence (sound recording)Autonomous sensory meridian responseSound masking