Siri stopped hearing me when in speakerphone mode right after my last software update to iOS 9.1! However, I can still talk to people and do other things normally.
Working:
- Voice memos
- Siri via headset
- Voice dictation via headset
- Speakerphone voice
Not working:
- Voice dictation via phone itself
- Siri via phone
I haven't resolved the problem and have a case opened with Apple Support. However, during troubleshooting, I learned the iPhone actually has 3 microphones as shown in this diagram from Apple:
