The dorsal cochlear nucleus, or DCN, is a small structure in the brainstem where signals from the cochlea make their very first synapse on their way up to the auditory cortex. Anatomically it sits right next to nuclei that handle input from the jaw, neck, face and upper spine. That neighbourly position turns out to be important.
It explains a phenomenon many tinnitus patients notice: clenching the jaw, pressing the temples, tilting the head or stretching the neck can change the pitch or loudness of the ringing, sometimes briefly silencing it. The somatosensory input reaches the DCN and modulates auditory firing. This kind of modulation is one of the clearest pieces of evidence that tinnitus is generated centrally rather than in the ear itself.
It also makes the DCN a leading suspect as the actual site where tinnitus is born after hearing damage. When the cochlea stops sending input at certain frequencies, the DCN's spontaneous firing rate appears to rise — and that increased firing, propagated up the auditory pathway, is what the cortex eventually perceives as a phantom tone. It is one of the most fertile research targets in the field.