Active noise control with tinnitus?

I've had high pitched frequency whines in my ear come and go since I was a kid, but only recently did it become a problem.

I was wondering, is tinnitus an actual sound your brain thinks it's hearing? Or is it the cause of over active stimulation, thus the interpretation of the noise. Most research I find on it, has no definitive answer.

I'd think that if it was a thing your brain thinks it's hearing, wouldn't active noise control with the inverse wave of the tinnitus sound cause it to be canceled out?