I don’t know about illusory hearing as related to RSD but I do know that I had similar issues most of my life.
I used to think people were looking at me, talking about me and sometimes thought that they could hear/guess my thoughts. Started when I was a kid. Found out it was ASD-1 and a brain tumor causing alot of the issues.
And the only way I found out about that was by going to the doctor. I really do recommend speaking to a doctor about these issues and you might be surprised with what they find and how much better you feel once you can get the right therapy.