If you're new to AirPods, considering buying a pair, or just want to pick up some new tips.
AirPods and AirPower: Everything We Know
Insight into Apple's Design Process
Pixel Perfect Mockups - While it adds time upfront, it "removes all ambiguity" and the need to correct mistakes later down the line.
10 to 3 to 1 - Designers mock up 10 different unrestricted designs for a given feature. From these, 3 are chosen for further development until a final one is chosen.
Paired Design Meetings - Two meetings. One is for free thinking ("go crazy") without worries about any technical constraints, while the other meeting addresses implementation and practical considerations. Both of these meetings continue throughout product development.