When I was little I got a toy that let me record sounds and play them back. While it did fine recording other people, when I listened back to myself recorded I thought it sounded so strange. This turns out to be really common; most people hate how they sound recorded.

So now I'm curious: I know how my voice sounds to me and how it sounds to you, and how your voice sounds to me, but how does your voice sound to you? I think the changes are probably mostly EQ, which means I could make something to figure this out. You would say something, then hear it back through a speaker with some EQ, and you would keep fiddling with the EQ's settings until what you heard back matched what you hear as you speak.

(I wonder if this would work well on TV to indicate when you were hearing a character's internal thoughts?)