How do I disable Voice Chat or mute microphone in Windows PC version?

My son just started playing this game and the voice chat feature is annoying and we can't figure out how to turn it off.  Once you start a game, we found out how to mute the sounds from all other players (thankfully, since otherwise you just hear a bunch of random noises and people talking in a variety of languages, with no filter for inappropriate or abusive language).  But, it seems that our microphone is ALWAY OPEN, with no option to turn it off.  Unless I just can't find it, this MUST be added to the options settings.  Our microphone is built in, so I can't just unplug it.  For now, I have disabled the input device in Windows, so I think it is off, but this is not really an acceptable solution.

Am I missing something, or can EA please fix this!