mac OS microphone only works when using Siri, works fine on bootcamp As the title says the mic only works in Mac OS when using Siri in any other application it is just muted, the input level in system setting is always 0 as shown in the picture unless I'm using Siri. The mic works just fine on Windows 10 through bootcamp which leads me to believe it is not a hardware problem.

I'm on mac OS Sierra 10.12.3, I tried resetting SMC didn't make a difference.
I had the same issue recently, and i found a seemingly stupid fix to it.

Go to system preferences, keyboard, and access the dictation and try using it on any document. The default to using dictation on my mac was double tapping Fn button. Strangely enough my dictation feature worked and typed what i spoke on the screen as Siri did. Then, go back to your input devices and check if that "permanently" fixed ur input issue; microphone should now also work without dictation being active.