I did some more reading on how the ear works and I think my comment on there being positive feedback is wrong. Looking at how the bits are laid out and wired up it looks more like it uses amplified negative feedback in the manner of an op amp. The diagram I looked at is in Purves et al, Neuroscience 5th edition. I'm now thinking the tinnitus may be from the input maxing out when the negative feedback breaks. From a practical point I've found carrying wax earplugs helps my ears recover.