iPhone 6 Dead Microphone

I didn't post an update but I finally fixed my dead microphone problem. What I did was take my iPhone to the Apple store. One of the geniuses ran an audio test which confirmed the microphone was bad. Since my phone was still under warranty they swapped me with a new one and I was on my way in about an hour. It took that long to make sure I had a fresh backup and update the OS on the fresh phone.

The many microphones of the iPhone 6

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: