Comfort noise( CN) is an artificially generated noise that is inserted during pauses in speech when telephoning. Since no background noise would be heard during pauses in speech when telephoning via digital networks, the comfort noise is inserted.
Without the superimposed noise, no background noise would be heard during pauses in the conversation, and the line would be dead silent. Since this can lead to irritation among the call participants, speech pause detection is used and the background noise is faded in during pauses in speech. The background noise is a pink noise, which is characterized by the fact that the energy density decreases proportionally to the frequency. Comfort noise is generated by a comfort noise generator( CNG).
Comfort Noise is equally used in ISDN and VoIP as well as in the various mobile networks. Comfort Noise adjusts the noise level, which is inserted during pauses in speech, to the level of the normal background noise. As a result, the mobile subscriber cannot detect any difference between the background noise during the call and during pauses in the call. Since the background noise is constantly changing, the Comfort Noise must also adapt to these changes.