A few words on echo.
When sound is played out from your speakers, it will be picked up by your microphone. If that sound is someone else's voice, it will go back in the microphone and sound like echo to the others. It's annoying.
In Hangouts, we use a piece of software to remove this echo. We basically scrub it away live.
As you can imagine this is a very complex thing to do, I call it black magic :) The piece of software that does this is called the Acoustic Echo Canceller, or AEC. Removing echo is done through complex maths.
The trick to well performing AEC is that it needs to properly time the voice being played out from the speaker to the voice picked up by the microphone.
The AEC is designed for personal use. Larger rooms can make this timing fail, as voices can come back from a wall far away. An external echo canceller, as mentionned here: can help.
The problem with echo is that when you hear it, it's not your fault. It is usually someone else's microphone that is picking up your voice. And if this happens, the AEC failed for the person on the other end, not you.
Here are some tips on how to be a good hangout citizen to avoid echo on your end.
1. Try using a headset. Laptops often have a built in microphone placed right next to the speaker. This can make it very hard for the AEC to perform properly.
2. Check to see if your computer is too busy. On windows, doing CTRL-SHIFT-ESC will bring up the task manager. Check that your computer is not overloaded. Without the proper ressources, the AEC won't be able to do it's job.
3. Turn off Audio Enhancements. Several computer manufacturers ship with so-called Audio Enhancements that ruin AEC performance. Shut these off by doing
• Right click on the speaker icon in the bottom right.
• Choose Recording devices.
• Right click on Internal Microphone and then select Properties.
• Select the Advanced tab.
• Uncheck Enable audio enhancements.
• Press OK.
4. Keep it simple. Use the same audio device to record and playback. Using USB speakers and the built-in microphone should work, but it makes things more complex.
5. Don't point the speakers at the microphone, and keep them at a distance if possible.
6. Update, update update. Make sure you have the latest audio drivers, service packs and updates. We have often seen how this solves issues.
Our work on the AEC will never be done, but you can help:
If people constantly complain that you are echo-ing, ping us. We'll likely ask for detailed system information and ask for some recordings from your computer. These will help us in making the next versions even better.