Cannot Select Internal Microphone When External Microphone is Attached

• Component: WebRTC
• Status: NEW ---

[Homerlex]

While developing a web application that uses WebRTC I found that on iOS I cannot use the internal microphone as an input source when an external microphone is attached.  Tested with Airpods and wired headsets

Here are the repro steps:
* Attach an external microphone to your iOS device
* In iOS Safari hit the following URL: https://webrtc.github.io/samples/src/content/devices/input-output/
* Notice that the echo you hear is coming from the external microphone (as expected)
* Change the selected "Audio Input Source" to "iPhone Microphone" (or "iPad Microphone" if using an iPad)
* Notice that the sound is still coming from the external microphone.  I would expect the internal microphone to be used at this point.


I've duplicated using iPhone mini (MG8F3LL/A) on iOS 15.1 with Airpods.  I have also duplicated on iPad Pro (MLMP2LL/A) on iOS 15.2 Beta 3 using a wired headset.

[Radar WebKit Bug Importer]

<rdar://problem/86153529>