User's Manual

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4.5.3  Audio
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Sections Description
EchoCanceller EchoCanceller:Toremoveacousticechofromavoice
communicationinordertoimprovethevoicequality.
 VAD(Voice ActivityDetection):AllowIPphonetodetect
thepresenceorabsenceofhumanspeechduringacall.
When detecting period of “silence”, VAD replaces that
silence efficiently with special pa
ckets that indicate
silenceisoccurring.Itcan facilitatespeechprocessing,
and deactivate some processes during non‐speech
section of an audio session. It can avoid unnecessary
coding or transmission of silence packets in VoIP
applications, saving on computation and network
bandwidth.
 CNG(Comfort Noise Generation): Allow IP phone to
generate co
mfortable background noise for voice
communications during periods of silence in a
conversation. It is a part of the silence suppression or
VADhandlingfor VoIPtechnology.CNG,inconjunction
withVADalgorithms,quicklyrespondswhenperiodsof
silence occur and inserts  artificial noise until voice
activity resumes. The insertion of artificial noise giv
es
the illusion of a constant transmission stream, so that