The real reason we hate the sound of nails on a blackboard

*Shudder*

Ever wonder why you cringe at the sound of fingernails on chalkboard, or a fork scraping across a plate, or the squeak of Styrofoam? Turns out, it's all down to these uncomfortable sounds' frequency.

Source: Universal Pictures via Imgur.com

In a new study by the University of Cologne in Germany, researchers had participants listen to audio clips of people scraping their nails against a chalkboard, monitoring the changes in each listener's blood pressure and heart rate. They also tracked changes in the electrical conductivity of their skin, to see how much the sounds made them sweat. The participants then rated each sound by its unpleasantness.

Turns out, the researchers found that it wasn't the high-range frequencies that caused the most discomfort, but actually the mid to low-range (2000-4000 hertz bandwith) frequencies that made the listeners' toes curl.

While there is no known scientific reason as to why this is, the scientists do have a few theories. First, the low frequencies are usually found in the sound of a baby crying, which could be our evolutionary reaction to responding to our child's needs. However, the researchers suggest the real reason we cringe is actually because of our ears.

Apparently, it all comes down to the shape of our ear canals, which just happens to amplify these specific frequencies. When noises fall within this range, they literally sound louder to us, making our hairs stand on end and giving us unexplained anxiety.

The scientists also believe there could be a psychological element too. When participants were told that the audio clip was nails on chalkboard, they were more likely to break into a sweat than when they were told it was 'experimental music.'

See, ignorance truly is bliss. Who wants to hear this distressing sound?

Source: Bustle.com

Answer? No-one. We're shuddering just thinking about it.