> Tinnitus is a condition when a person hears a ringing sound or a different variety of sounds when no corresponding external sound is present and that other people cannot hear.
That’s called tinnitus. And I agree, it isn’t rare. From TFA, roughly 15% of people have it (that report it).
Sounds like you may have severe tinnitus, which is more rare, limited to 1-2% of people.
Some people even have multiple frequencies of tinnitus at the same time.