Odds are, you hate at least one, or maybe all four of these sounds: Nails on a chalkboard . . . chalk on a chalkboard . . . a fork 
scraping against a plate . . . and Styrofoam squeaking.
–A new study in Germany tried to figure out WHY we hate those sounds . . . and why they make our arm hair stand up. And the researchers have an answer.
–Those sounds are all in the range of 2,000 to 4,000 Hertz. Our ear canals are designed to amplify sounds in that range. So when we hear them, they’re LOUDER on our ears than we realize . . . and that makes our brains think we’re in DANGER.
–That makes our arm hair stand up, because we’re on high alert, which changes our blood pressure and the electrical conductivity of our skin. It also makes us hate those sounds, because we perceive them as dangerous.
