I was careful to not bother a friend's father at a gathering because he seemed to be listening to something on his AirPods. Only after did my friend let me know

I was careful to not bother a friend's father at a gathering because he seemed to be listening to something on his AirPods. Only after did my friend let me know he uses them in hearing aid mode (didn't know that was a thing!) to hear better. (Father won't admit he needs hearing aids, but is happy to use AirPods to assist. )