Sound monitoring
Using sleep monitoring app: to detect breathing/snoring sounds, app says"go to Settings > Motion detection," to turn on microphone. I can't find that. (iPhone Xs)
iPhone XS
Question marked as
Well, OSxDaily gave me a pointer: Go to Settings > Privacy and Security > Microphone.
On this page, I found that the microphone, although turned on for all the other apps listed, was not on for the "Sleep" app. Moved the slider to "On". Satisfactory solution.