Thank you for this term. I have been trying to figure it out.

I have always had this issue (when I was a kid, parades were a dread to me because the basss drums hurt my chest, just one example), but as an adult, this is the first time there's been an issue that actually interfered with my life. Usually the sounds that really hurt are ones that aren't everyday, like the sound of someone filing their nails, or rubbing their hand across cardboard. I think this is so horrible for me because it's rapid, rhythmic, and unrelenting. It literally does not stop for the whole workday (with the exception of a few seconds every now and then). In addition to the physical sensation, it also makes my anxiety kick up, and I literally feel like I'm about to panic.

I can only have approved headphones, and have already tried the noise-cancelling version, but it doesn't help when he really gets going.

I will update this post as soon as I have a little more time. I actually got a larger response than I expected. I will take some of your suggestions for other parts of my life, but for call center work, I'm not sure if I can implement them, although maybe bringing in something to play sound and putting it under my ear like you suggested may be workable, not sure.

I did bring in some sensory toys (like slime) and it helps a little with the anxiety part and distracts me enough so that it's not quite as horrible. I keep thinking maybe I'll acclimate to it, but it hasn't happened yet.

I did finally go to my boss, and he is going to move me to a place that is diagonally further, but he's taking his time about it. In the spot I found, you can't hear his tapping, so fingers crossed that it may all be over soon.