Phase is a physical property of sound waves that cannot influence a signal originating from the brain or cochlea.

Yea, but he proposed shifting the phase of the physical signal (16.5khz) which supposedly matches the frequency of the imaginary signal.

I still think it's unlikely to work.

I understand, and there could very well be some psychoacoustic cancellation when stimulating with a matching tone. But any effect will be regardless of the phase of the signal, because phase cancellation is a physical effect of sound waves that occurs before they are converted to neural activity (where tinnitus originates from).

In simpler terms: tinnitus does not have phase, at least not in the same way a sound wave does.

Neutral activity itself definitely takes phase into account somehow, since you can hear the phase difference of two same-frequency tones being played independently into each ear, without any kind of sufficiently strong mechanical connection that would explain it.

I experimented with this when I was young and I concur - it's really like this. Astonishing but that's how it works.

I think though that the brain is also considering the spacial relationship of the sound to the listener. Hearing the sound from an external source rather than "inside your brain" does provide relief in my experience.

Doesn't mean you can't match it.

It's fun to test what happens when you play the same wave through your headphones but one channel is inverted.

Funny enough lots of stereo widening magic relies on a physical property of sound not existing when it's in your head.

If you ever wire a loudspeaker channel the wrong way around, it feels very weird as a lot (but not all for a stereo mix) of the sound will cancel with the other channel in the middle of the speakers and you can move your head through this dead zone.

I've never tried it with headphones, but I suppose even though destructive addition isn't going to happen it might affect things like intended spatial perception.

Happened once when prepping for a language aural exam. With no immediate fix and the start of the exam pending, we moved some desks instead!

AFAIK when there is not enough external sound input, the brain amplifies the signals from the inner ear in an attempt to compensate which leads to hyperactivity in the auditory nerve and auditory cortex, which can be perceived as tinnitus. So you cannot cancel a 'signal' that doesn't exist. This is my understanding and I may be wrong.

What I've done is to tune a sine wave to match the frequency of the tinnitus, then notch that frequency in white noise, and blast the result for a few minutes. My tinnitus has not been permanent, it's just the rare occasion where I forget earplugs for a concert, and come home work ringing in an ear.

This technique makes the ringing go away for a while, but it creeps up again after some time. Thankfully, it has always completely gone away after a day or two.