Measures whether the microphone and the model agree with a real guitar.
Run the self-test before the microphone. It proves the model computes correctly on this device — worth doing on iOS, where WASM has previously returned wrong numbers without failing.
The two iOS questions the app cannot answer for itself: does our own sound leak into the microphone, and can playback reach the loudspeaker at all. Each button asks for the microphone if it needs it.
An open microphone pins iOS output to the earpiece, and the category that reaches the loudspeaker refuses capture — there is no web API for both. Report two things: whether the note was loud, and whether iOS asked permission again.
Run this on speakers, not headphones. It plays a tone while recording, to find out how much of our own audio the microphone hears.