Why are we annoyed by certain sounds?

Nails on a chalkboard is the classic, but personally I can’t stand the sounds of people eating. Especially slurping and/or lip smacking sounds, or anything above and beyond normal chewing with your mouth closed. Once I was stuck on the greyhound for like eight hours next to this old lady who removed her dentures and proceeded to very slowly eat some pork using nothing but her gums.

I think loud eating sounds are revolting. It literally makes me feel nauseated. Sometimes I wonder if people just don’t realize they’re being so noisy, or maybe they don’t realize they’re doing it at all. I know it’s super neurotic for me to feel this way, and if anyone told me something like, “the sounds you make are gross” I would be mortified. So I just deal with it, find some headphones, or try to politely leave as soon as possible.

But what I want to know is, why are some sounds such pet peeves? What is it about nails on a chalkboard, eating noises, or songs like “Never Gonna Give You Up” that drives people up the wall?