There is no sound in your mic (Windows)

Possible reasons:

microphone volume level is too low or muted
a student keep silence with active noise reduction (typical for laptops)

Perform the following steps:

Try speaking while the system check or make other noises (snapping your fingers).
Examine if your microphone follows the sound you make (check the green indicator next to it).

Check microphone properties and make sure that the volume level is not too low and that the microphone is not muted.

Click OK.

For example, here is a muted microphone with low volume level:

Also:

Дать доступ к веб-камере и микрофону