‘I don’t know about tinnitus. I’ve only just received the AirPods so haven’t studied them in detail. The ANR is very good, it cancels out 90% of the ambient noise and the sound quality / range probably exceeds what my ears are capable of hearing. Pass through mode is interesting, I can hear conversations and ambient noise whilst listening to music / radio streaming off my Apple Watch. I do a lot of walking with my dog, so they are great for when I’m out with him.
The inside ear microphone is probably used to make sure the AirPod is sealed into your ear properly and that no ambient noise is “leaking“ in. There is a fit diagnostic App which tests the seal and this must use the inner microphone. I have just remember, a microphone is used for the ANR too. About 30 years ago I used an Alpha flying helmet set up for ANR to deaden two screaming RB199s. That had microphones in the ear cups. Worked well too, just a gentle whine whilst all hell was breaking loose outside.