It's because u disabled steam voice from the config.ini file. I know it's annoying to hear u'r opponent mashing, rageing, farting or whatever... but u need to have steam voice to "true" valor in that file. U can turn off mic from windows settings and kindly ask u'r friend/opponents to do aswell.
I get the loud mic issue that effects people I am playing so I had to edit the file and also get the memory error myself. Issue is I don't have a mic connected to my pc yet its feeding back to people that play me. It makes no sense!