where is the mic on HTC ONE M9

[AC Question]

I can hear a caller but they can't hear me

 

[B. Diddy]

Welcome to Android Central! The primary mic is under the lower speaker grille: https://www.ifixit.com/Teardown/HTC+One+M9+Teardown/39166

Can the caller hear you if you turn on speakerphone (which typically uses the secondary mic at the top of the phone), or if you use a wired or Bluetooth headset?