If echo is still heard during your research session, it's most likely caused by one or more end-point devices.
We recommend the moderator and test participant use headphones whenever possible. Try unplugging and replugging in your headphones if you hear an echo.
If you're using your desktop speakers, start by lowering the output volume.
If this does not fix the issue, the moderator and test participant should stop the session and restart Chrome before rejoining the session.