If it’s changing, you might want to get a brain-scan, immediately.
No, it isn’t normal ( not for me, anyhow ), to the guy who said it is normal.
It’s not an ear thing, it is an auditory-processing thing, so it’s your brain that’s doing it.
The question is why it is doing it.
Perhaps it’s just fuzzy wiring, as most such cases likely are.
( synaesthesia is a case of weird wiring, and I’ve got that, but not in the normal way, not senses blurring into each-other, but rather my non-visual cognition being a kind of “blur” to those senses, so they mesh oddly )
But if it begins changing in either intensity or character, get a scan.
( I’m a braindamage survivor, and it takes decades to adapt to braindamage: prevention/avoidance is better than hating one’s life for decades, while being bullied by all who reject that it could still validly be a problem, and hold that one ought either force oneself into being an “acceptable” drugged psychiatric-zombie, and not “pretend” to be getting better, or one ought be able to be acceptable-pretence, just like Valid People™ are. )
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https://www.funtoo.org/Welcome
instead of Gentoo.