Once a user is enabled in a Full-Duplex channel, its microphone button in the toolbar - that until then is disable - passes to an active status. In this moment the user sends its audio and video. All the users in the conference room listen and see the enabled user.
PC & Mac: microphone button
Tablet & smartphone: microphone button
If you need to stop sending your audio, press the button to deactivate it (in PC & Mac you can also use the main horizontal menu -> Channel -> Enable/disable webcam and microphone).
Please note that in PC and Mac a click on the webcam button disable both webcam and microphone buttons at the same moment. If you need to use a “only audio” communication, press once the webcam button (disable both), then press the audio button (turn on only the audio).
You can turn off your video also if you have some connectivity problem (not enough bandwidth): in an only-audio mode you will use less connection.