If you've ever been in an old fashioned classroom, you understand the aches and pains your ears suffer when a classmate scrapes their fingers along a chalkboard. Every piercing squeak causes a shiver to go down your spine and instinctively you muffle your ears with your palms. Although most of us have experienced this, little of us have asked why we respond in that way? Take the time with me now to understand what researchers believe to be the cause of this phenomenon.

Our reaction to fingernails scraping along a chalkboard is primal. It has the same frequency of a crying baby and a human scream. Hearing these frequencies start up our survival instincts. Our bodies react with stress when we hear fingernails on a chalkboard the same way it would react in either of these situations. Based on a study, it is believed that for human communication and survival our ear canals have evolved overtime to amplify certain frequencies between 2,000 and 4,000 Hertz.

Although this information comes from studies, it is all speculation until further research. In the meantime, though, we can stick to white boards.

Information from https://www.livescience.com/57106-why-fingernails-on-chalkboard-hurts.html.