comfort noise generator (CNG)

CNG is part of the silence suppression or voice activity detection (VAD) handling for VoIP (Voice over IP) technology. The purpose of VAD and CNG is to maintain an acceptable perceived quality of service (QoS) while simultaneously keeping transmission costs and bandwidth usage as low as possible.

CNG, in conjunction with VAD algorithms, quickly determines when periods of silence occur and inserts artificial noise until voice activity resumes. The insertion of artificial noise gives the illusion of a constant transmission stream, so that background sound is consistent throughout the call and the listener does not think the line has gone dead. Most conversations include about 50% silence. VAD software allows a data network carrying voice traffic over the Internet to detect the absence of audio and conserve bandwidth by preventing the transmission of "silent packets."

CNG uses special algorithms to create artificial noise that matches the actual background noise it detects on a call. The generation of background noise helps avoid noise modulation that might otherwise occur if voice transmission were completely switched off during silent intervals. There are a number of reasons to suppress noise modulation. For one thing, noise modulation may be so different from natural background noise that it is unpleasant for calling parties. Furthermore, it may reduce the intelligibility of speech when spoken communications resume.

The use of VADs and CNG has been estimated to reduce bandwidth requirements for a group of voice channels by as much as 50 percent.

Learn more about Telecom Network Management

Do you have something to add to this definition? Let us know. Send your comments to techterms@whatis.com

More resources from around the web: - CommsDesign.com explains 'Generating Noise in VoIP Designs.'

FILE EXTENSION AND FILE FORMAT LIST File Extension and File Format List: A B C D E F G H I J K L M N O P Q R S T U V W X Y Z #

RELATED CONTENT Outsourcing strategies for next-generation network operations Learn how outsourcing strategies for network operations help telecom service providers deal with issues like complex next-generation networks and... Global Crossing re-engineers the telecom customer experience Global Crossing has made customer experience central to its business and combined its CTO and CIO executive positions to reflect new network hardware... Network traffic management targets access and 'middle mile' aggregation infrastructure Increased traffic management , with techniques that focus on the 'middle mile' aggregation and customer access networks, help carriers transport...

RELATED GLOSSARY TERMS Terms from Whatis.com − the technology online dictionary backbone  (SearchTelecom.com) caller ID spoofing  (SearchTelecom.com) Caller ID spoofing is a service that allows a caller to masquerade as someone else by falsifying the number that appears on the recipient's caller ID...