Microphone is mute.

Upon upgrading from Peppermint 3 to Peppermint 4, microphone is mute, or doesn't work. Or perhaps it just doesn't work in Google Voice. I receive audio of the person I'm calling, but that person can't hear me. I've tried a couple different mics to make sure it wasn't the microphone itself. It was working fine in Peppermint 3. Went to Volume Control Settings (alsamixer) and arrowed through to "Auto-Mut" and disabled that, that wasn't it. The rear microphone levels are at max. Beats me. Also is there a way to test the microphone without calling someone? This (Google Voice) is really the only thing for which I ever use a microphone. Thanks. MIKE.