Echo Issue in large audio conferences


Features Used: Audio conference (approx 10 people) + screen share.
Issue: In between of the call, there is a “lot of echo”


  1. Initially everything is smooth and fine.
  2. But gradually, we can notice lot of echo from almost everyone — This is a serious problem.
  3. But when I tried with fewer people, I couldn’t notice this.

Something similar to this is fixed in last few months?

And also can you suggest, which part of licode I need to refer to fix this?

Thanks & Regards,

Licode doesn’t reduce/cancel echo by itself. This mechanism is part of Chrome/Firefox browsers, so it might be due to some change in the code. The more people in the room with their mics on the more likely the conference is to have echo issues.

There are some recommendations to avoid such an issue:

  • All participants should use headphones.
  • You can implement some Push-To-Talk mechanism to guarantee that someone who is not speaking will not send echo from their side.
  • Tell people to restart their browsers from time to time between conferences because echo cancellation stops working at some time if browsers remain running during long periods of time.

Sometimes … it is almost like, we are hearing our own voice.

yep, that’s quite common with echo issues.

Firstly, Thanks a lot for your support, Great Help.

[1:53:21 PM] Hemanth Anakapalle: “WARN: dtls.SSL - error in SSLv3 read server hello A”
[1:53:29 PM] Hemanth Anakapalle: “WARN: dtls.SSL - error in SSLv3 read server session ticket A”
[1:53:42 PM] Hemanth Anakapalle: “WARN: dtls.SSL - error in before/connect initialization”

Any of these logs can have effect on echo?

And in general, these warnings can be ignored (or) we need to fix these?

@HemanthAnakapalle, One source of your echo problems may be hardware related. Some laptops (and other computers) have quite problematic soundcards. It is not unknown that some soundcards “leak” more sound from output to input than is healthy. The separation of input and output in the analog circuitry is not sufficient and echo happens even without an actual microphone. In such cases the echo cancellation method used in browsers may not be sufficient, they are more able to work with acoustic feedback.

Hence it might be worth the effort to have a look at individual devices. Some of the devices may add more than its share of echo.

Is there any way to handle this in application?

And another note is, we are not noticing these kind of issues in GoToMeeting.

Advanced echo cancellation and feedback removal solutions are fairly common in the field of professional audio. But they tend to require specific software and/or hardware.

The easiest software fixes could be to use a gate (remove sound that is below some level) and compression (reduce the dynamics of sound above the gate level), but I do not know if they can be handled in JavaScript running in a browser. I assume they can (I have seen some implementations for quite similar things), but I have not personally tried that. In addition, I do not know whether those fixes would solve your problem.

Of course you can add a processing layer to Licode (there are quite good libraries available) and try some fixes in the browser, but those steps may require unreasonable amount of effort.

Easiest way would be to find the problematic hardware and get rid of it (if the problem is hardware related).

Thanks … we will identify the device through which echo happened.
And will debug further. (Problem is Issue is not consistent)

Mostly we may need to consider some way to handle these kind of things in application also.

@HemanthAnakapalle, were you able to solve this?

We had some cases in which external sound cards were necessary in order to get reasonable quality.