NSAlwaysAllowMicrophoneModeControl
A Boolean value that indicates if a person can configure a microphone mode regardless of whether the microphone is in an active state.
Discussion
When your app is in the foreground, use this key to allow someone to configure their microphone mode — automatic, standard, voice isolation, or wide spectrum — before activating the microphone. For example, a person can configure the microphone mode to voice isolation before starting a call in your teleconferencing app.