Mine is due to hearing damage from being stupid.

I can modulate it as well using my jaw muscles.

What I’ve always found interesting is that I can’t describe the sound. It’s high pitched, but I’ve never found a frequency of tone that matches or even comes close to the tinnitus.

I would imagine the signals my brain receives from the damaged nerves is very complex. Not white noise, but probably the equivalent of a tone with lots of specific harmonics.

As for my experience, it’s been an issue for so long it doesn’t generally affect me. It’s always there and I can’t ignore it, but it doesn’t disrupt my life, other than having generally not great hearing.