If you connect via your computer and choose your webcam, you will see yourself! You won’t hear yourself in any scenario, and please don't try to have the audience console open at the same time in a different browser window, as it will create a weird echo effect!
Rest assured that audio is flowing through if you see the "waveform" animation moving with your voice, which is located in the located top right corner of the Presenter Interface. You’ll see the animation move with your voice once you connect your computer audio or webcam.
Click on the microphone located top right corner of the Presenter Interface to mute or unmute yourself. When the icon is crossed out and the "waveform" animation is not moving, you are unmuted.