STEM Matters: Eek! The Screech!

STEM Matters Manager: Marisa Ostos 

Although some may find it less perturbing than others, certain sounds such as the squeak of styrofoam or the scrape of nails of a chalkboard can make someone squirm to the edge of their seat. Perhaps you are one of those people, but have you ever stopped to wonder why that may be?

Amazingly enough, research has been done studying this exact thing (and yes, research participants have had to listen to these sounds in the name of science). When you hear the sound of nails on a chalkboard, you might imagine that the high pitch of this sound is what causes us to cringe in our seats. However, a study done in 1986 found that it was the medium-pitched frequencies in this sound, rather than the higher pitches, that brings about our reaction.

More recently, research has found that the frequencies of these unpleasant sounds that lie between 2,000 and 4,000 Hertz may be the cause, rather than the actual “scrape” of the sound. This frequency is also the frequency at which we speak, oddly enough. Our own ear canals are shaped in a certain way which help to amplify sounds within the 2,000 to 4,000 Hertz range, so it is possible that unpleasant sounds are also amplified in our ear because of this.

What’s interesting to note that in doing research, these sounds were found less difficult to listen to when they were associated with a different source. For example, if some participants listened to the nails-on-a-chalkboard sound and were told the source, while others were told that this same sound was from a musical composition, people tended to react less. It is also interesting to note that the body does physically react to these sounds: Skin conductivity, which is a way to help measure your body’s stress-levels, does change significantly when you listen to these sounds.

Now, if all you can do is try your best not to think about these horrendous sounds as you read the article, here’s a bit of a positive note. Because scientists are actually doing research on this subject matter, steps are being taken to eventually reduce the frequencies of these sounds in everyday life, including “factory machinery, vacuum cleaners, and construction equipment,” to name a few. Let’s give a high-five to science!

*Source: Geere, Duncan, “Why Fingernails on Blackboards Sound So Horrible,” Wired UK.