system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why do some noises, like chalk scraping against a blackboard, or metal scraping against metal, produce unpleasant sensations in the body?

Like, when I hear chalk scraping against the blackboard, I'm fine; it's my classmates who clutch their ears. however, when I hear metal scraping against metal, I almost feel like something inside me is *vibrating* in a really unpleasant way. Does anyone know why this stuff happens?
gpt
Due to the similarity of the sound of your teeth being damaged. It goes way back ages to foraging where food sources like grains and berries may have grit or small rocks mixed in, and the sound makes your body instantly have a reflex against it.