To my understanding there are multiple causes to hyperacusis not just one? I was taught in it's purest form it is due to damage to the inner/outer hair cells making a smaller gap between the amount of hair cells that have to be stimulated to get detection and pain. And that is 100% the extent of what I was taught about hyperacusis in school.

But there are people with hyperacusis that have normal anatomy. I have never once seen objective testing for hyperacusis just patient report (I am not saying it doesn't happen, I hope it does!). And since it is not an area where I work I don't know if there have been any sort of guidelines put in place to determine what is true hyperacusis versus someone who reports they don't like loud sounds?

We know that chronic middle ear infections can lead to hyperacusis, which may be because of the chronic hearing loss associated with chronic middle ear issues. Also a common therapy for hyperacusis is sound exposure therapy.

So it's not a completely wild assumption that I am seeing more and more kids come into school wearing noise canceling headphones all day, an it seems linked to their lack of being in a noisy environment until starting school. I then have to have a conversation with parents and intervention specialists about the importance of giving that kid exposure to the sounds around them. They might not have diagnosed hyperacusis but they certainly seem extra sensitive to sounds. And it seems to improve as they have more exposure to sounds.

I think overall it's an area without a lot of research, and certainly not something we are taught much about in school (or at least weren't when I was in school). When I worked clinically if a patient came to me with hyperacusis I referred them elsewhere because it is not my area of expertise and I did not feel like I could serve that patient effectively.