A few years ago, I took a hearing test from Costco to see if I needed hearing aids:
The top lines are clear enough (level of hearing loss, by left/right ear, through air or bone conduction).
But there are two additional lines at the bottom with U symbols (or perhaps ∪), and I can’t find any information online about what they are supposed to represent. (Certainly I don’t have hearing loss anywhere near the 100+ dB level)
I don’t remember them ever having played loud sounds for me (and seems like 100 dB+ would be deafening?), but it was a few years ago, so maybe I just forgot. Or maybe the person just put in fake numbers because I didn’t need hearing aids anyway.