Coordinated Reset neuromodulation, a protocol developed by Peter Tass. Four short tones spaced around your tinnitus pitch are played in jittered order at roughly 1.5 Hz with a 3-on / 2-off pattern, at a low, just-audible level. The theory is that the sequence desynchronises pathological neural firing in the auditory cortex. Clinical evidence is mixed but promising. HushOS offers an acoustic version of this, not a medical device.