Written by Andrew Low,

How Does Echo Cancellation Work During a Video Conference?

We have all experienced our voice echoing through laptop and meeting room speakers or headphones during a video conference with clients or colleagues. Even if it only occurs for a few seconds, it is extremely disruptive and may pause or stop the flow of a meeting until the issue is resolved. As video conferencing becomes an increasingly essential element of business communication, it is important to understand echo cancellation in order to prevent or resolve the problem.

Why do you need an echo canceller?

An acoustic echo canceller is needed on both sides of the call during a video meeting to avoid echo. When one of the participants in the conversation begins to speak into their microphone, the signal is transmitted through a bridge, VOIP system or the Internet, which will delay the signal. This signal is then broadcast through the loudspeakers in the listener’s room and picked up by their microphone. The delayed signal is then transmitted back to the original speaker’s room and heard as the echo of their own voice. Like feedback, this is a situation that will derail a meeting.

What does echo cancellation do?

An echo canceller on the listener’s side hears both the signal being picked up by the room microphones and the incoming audio that is sent to the room speakers. When it determines that the signal being sent out is the same signal that came in, it electronically cancels it so that signal does not transmit back to the talker’s loudspeakers, thus cancelling the echo.

Although the echo canceller on the listener’s side benefits the talker, there must be an echo canceller on both sides in order to prevent either side from experiencing echo to have a full duplex meeting. If you are hearing the echo of your own voice, it is actually the fault of the person on the other end of the call because they do not have a working echo canceller in their system. They are essentially allowing your voice to come back to you.

Audio Basics for IT Professionals

This topic and other essential audio basics for IT professionals are covered in the below webinar. Gino Sigismondi and Chris Lyons from Shure, teach IT professionals how to navigate the blend of analog, digital, wired, and wireless technologies that combine to deliver high-quality sound for meetings and conferences. Special attention will be paid to how audio signals can co-exist with office functions on a corporate network.

People tend to assume that if there’s a microphone anywhere in the room, it will pick up their voices clearly. Microphones designed to pick up speech are directional, however. That means that they pick up sound best from one direction: the front.

If you speak into the side of the microphone, near the microphone, or next to your neighbor’s microphone, your voice will be hard to hear. Position the microphone directly in front of you, face it toward you, and then speak directly into the front. This will give you crisp, clear sound.

About the Author

Andrew Low

Andrew is Systems Marketing Manager for the UK. When not focussing on installed audio, he can be found in the basements of London pubs playing his guitar, badly. A London resident for ten years, Andrew took the leap across the pond after studying at the School of Audio Engineering’s NYC campus. He still struggles to understand the local “language”.

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