After reviewing your post, I understand your issue to be that the microphones aren't working with certain apps. The following article has some troubleshooting steps that can be done to help with this issue.
Get help with the microphones on your iPhone, iPad, and iPod touch
Get help
If you still have issues after testing the microphone on your device, try these steps:
- Unplug any accessory plugged into the headset jack.
- Avoid blocking the microphone and iSight mic with your fingers while holding the device or recording video.
- Remove screen protectors, films, or cases that cover the microphone, iSight mic, or iPhone receiver.
- Clear any debris from the microphones or iPhone receiver. Refer to the user guide for your device on microphone locations.
- Restart your device.
- Make sure you have the latest version of iOS.
If you've tried these steps and people still can't hear you on phone or FaceTime calls or Siri doesn’t hear your requests, contact Apple Support.
Thanks for stopping by the Apple Support Communities. Have a fantastic day!