If not, move on to the next fix.
Bad and outdated drivers such as those for your microphone and other audio devices could also be the cause of your mic not working properly.
To do this, right-click on the desired device and select Disable.
Turn on Overlay for the specific game and now you can play it with Overlay on as you wish.
After that, you can restart your CS:GO and check if the voice chat works properly.
Set to 1 to make the volume of voices change based on the distances between players.