I use linux mint 20.1
When I try to use mictests.com on firefox, test fails. Firefox says this: Testing failed because your microphone could not capture any sounds. Please make sure your microphone is not muted and try again.
arecord/aread work:
arecord -f cd -d 20 –device=”hw:0,0″ cica.wav
aplay cica.wav
All other mic tests behave identical, do not work on firefox, but work on chromium/opera.
I could not find any hint in the web.
In the mean time solved, see my comment below.