I'm 19, I never listened to loud music, let alone for long periods of time, and I have a pretty quiet very high pitched noise in my ears when it's quiet (like at night). It sounds kind of like the whine of a CRT. I've had that for years and I have no clue why, it's not like I go to concerts often or get exposed to loud noises.

My phone has a db meeter in the settings for my Bluetooth anc headphones, and I never go above 70dB and it's plenty loud for me

It doesn't really bother me because with the slightest noise I don't hear it anymore but it's still a bit annoying, I have to put some kind of sound to fall asleep (like the radio) just because otherwise I start to focus on the sound and just can't sleep