HH
1003 VoIP Speaker Phone
VSMPG
6. ECHO CANCELLATION
6
Echo Cancellation
6.1
What Is Echo Cancellation
Echo cancellation is a method to reduce energy returning from a speaker to a microphone.
The reason for using echo cancellation is presented below.
6.1.1
Headsets Are Usually Not a Problem
PC
PC
Speaker
Near−End
Speaker
Far−End
FES
FES
FES
NES
NES
FES
NES
Internet
NES
Figure 6.1: VoIP Conversation using Two Headsets
VoIP protocols like Skype are typically designed to work with headsets that have good
separation between the earphones and the microphone.
Figure 6.1 shows two telephone application users who are both using headsets. Because
there is no significant leakage between from the earphones to the microphones, there is
no disturbing echo.
Rev. 2.20
2009-12-07
Page
20(30)
