A team at Apple's Machine Learning Research Center recently discovered that headphones can be used to estimate an individual's respiratory rate.
Long-term respiratory measurement
Concretely, the headphones can hear inhales and exhales during physical exertion thanks to on-board microphones. This capture offers a low cost and non-invasive method to, for example, follow the progression of diseases, and cardio-respiratory health in the long term.
AirPods, new medical assistant
The document does not cite AirPods, but one suspects that if this research materializes, it will materialize first on Apple gadgets. Especially since rumors have already indicated that the company is working on integrating a heart monitor into its wireless headphones.