This is the weirdest problem. I am a uni student and I use firefox to watch my online courses. We mainly use google meets and zoom.

Today for some weird reason I can't hear when someone is speaking, although all other sounds come through ok. I had to use another browser. Youtube plays fine for example even the sounds in meets when someone logs in or out are playing fine but no voices. I did check some audio settings both from meets and windows and everything seems to be set correctly.