It is definitely cultural (as in, eating quietly is not a widely practiced discipline outside of "The West"). Slurping soup is actually polite and expected in Japan (probably in China and the Koreas as well. Well, when they have soup in North Korea). My African friends are all loud eaters, as well. I try to respect the cultural difference despite it hurting my misophonic brain. But not from American lards. No Sir. Eat like a fucking American you pigs!