耳 ear

This one looks like eye (目) but with a bunch of lines sticking out from it. Right? OK, so let's try to remember it like this: The ear is a sense organ like the eye, and the lines sticking out are way too many piercings.

earplugs ★★☆☆☆ KUNKUN

hard of hearing ★☆☆☆☆
耳 (ear) + 遠 (far) = 耳が遠い (hard of hearing)

tinnitus ☆☆☆☆☆
耳 (ear) + 鳴 (animal cry) = 耳鳴り (tinnitus)