What's the typical onset? (Since I remember <10 years old, I heard some noise and just accepted it as amplifier-like-no-signal-noise, even though regular hearing tests measured above average hearing. Though they don't cover the whole audible spectrum usually :/)
Same for me. Remember the noise since I was a small child. Always thought it was normal. Hearing tests consistently come back perfect.
But yeah, hearing tests cover a very tiny portion of the spectrum. Audiology, in this regards, seems to be completely divorced from the frequencies people hear in real life. In reality, the vast majority of hearing tests barely cover the frequency range of human voice - let alone frequency ranges for music or even tinnitus.
I asked my audiologist if it might be possible to cover a wider range of frequencies and she seemed flabbergasted that someone would even request such a thing.
So, yeah. If you have tinnitus, or music isn't sounding as nice to you anymore, or for some reason bass frequencies sound off - well, you won't find out with a traditional hearing test.
I'm not exactly sure which tests you've gotten. It may be the case that the audiologist will only test a few frequencies for someone who is likely to have good hearing. But if you are fitted for hearing aids they will test a range of frequencies from 100 Hz to 8000 Hz.
Almost all cases of hearing loss have hearing loss at high frequencies, so they may be able to screen you by just checking at higher frequencies. As far as I know, losing bass frequencies first only comes from specific conditions like Meniere's disease.
8K seems too low. Sure at 20K you wouldn't hear anything, but there's still a lot of potential to hear a low level hum at let's say 13K which drives you mad.
Were you ever in a school band? I was in every band class the school offered from grade 6 thru 12 and I attribute my tinnitus to constant loud instruments every day in those enclosed spaces. Four of those years I sat directly in front of the percussion section in a tiered seating layout, where my ears were exposed to snare drum and cymbals from mere feet away. I have constant ringing in both ears... fortunately it isn’t debilitating for me. I hope awareness around ear protection continues to grow.