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Why Is the Sound of Fingernails on a Chalkboard So Irritating?

When the strings of a guitar are out of tune, the discordant results are noticeable.
A chalkboard.
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  • Written By: Michael Pollick
  • Edited By: Bronwyn Harris
  • Last Modified Date: 07 April 2014
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There are few natural sounds more irritating that fingernails on a chalkboard, with the possible exception of foam cups rubbing together, a squeaky door hinge, or a dentist's drill. What seems to set the sound of fingernails apart from other irritants is the apparent universality of it. Few people living on the planet can avoid cringing in agony as the high-pitched scraping noise begins, and everyone is relieved when the event is over. No one can say with any scientific certainty why the sound is so incredibly irritating, but there are a number of interesting theories.

Some believe the sound is similar to an animal's high-pitched screech indicating danger to the rest of its group. Macaque monkeys, for example, have been known to emit a warning noise of relatively the same pitch and duration of the dreaded fingernails on a chalkboard sound. It has been suggested that humans react to the sound instinctively, creating a "fight or flight" response.

Another theory holds that the sound of fingernails on a chalkboard is akin to the scraping sound of rocks against teeth. Scraping noises are especially irritating because they remind us of painful dental experiences or the unpleasant sensation of biting down on a piece of rock or metal. The scraping sound is created by the fingernails alternatively slipping against and gripping the rough surface of the chalkboard. Experiments conducted by scraping a garden tool against a chalkboard demonstrated that the lower frequencies of the noise were especially bothersome.

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In a similar vein, some have theorized that it's not the sound, it's the action itself. Anyone who has ever scraped his or her fingernails against a chalkboard is not likely to forget the experience. As the fingertips drag across the rough surface of the chalkboard, a number of nerve endings are stimulated, and not necessarily in a good way. When people hear the sound, it is highly likely they will have a sympathetic response and identify with the unpleasant sensations accompanying the sound.

Sometimes it's a matter of harmony versus disharmony, auditorily speaking. Many people are very sensitive to changes in pitch or frequency. A guitar with one string out of tune can disrupt an entire performance, for example. The attention signals generated by local television stations are often irritating for a reason. The emergency signal has been detuned in order to stand out from normal background noises. The ultimate in irritating and detuned harmonics is most likely the sound generated by fingernails on a chalkboard. There is simply nothing remotely harmonious about that screeching, abrasive sound, so we react strongly whenever we're forced to hear it.

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Discuss this Article

anon944458
Post 10

"with the possible exception of foam cups rubbing together, a squeaky door hinge, or a dentist's drill"

Really? Squeaky hinges and dentist's drills never bothered me. Foam cups are a bit annoying, but nothing awful. But I absolutely cannot stand the sound of scraping a chalkboard.

anon938961
Post 9

Actually, the screeching noise doesn't bother me too much. However, the sound of a traditional dull pencil on paper does.

anon267565
Post 8

Fabulous how ignorant we are about something so seemingly basic. I am Swedish, my friend Russian, and you who write probably American, and we all shudder at this sound, but no one knows why. We've got a lot to learn, even about the basics.

anon154329
Post 7

The sound doesn't bother me at all. However, lots of sounds that other people don't seem to even notice, bother me very much.

anon108812
Post 6

I actually like this sound and it's a plus for me that it bothers people. I think i would fight in the danger situation.

anon105376
Post 5

Some flash-bang stun grenades generate a similar sound.

anon105199
Post 4

I'm a little surprised that there was no mention about the slight similarity between the sound of fingernails scraping a chalkboard and the sound of a baby in distress, and similar cries of distress in humans. It makes for an interesting psychoevolutionary bit of information.

I really wish all of these articles would cite their sources when possible; it would make great additional reading and would give credibility to the claims in these articles.

anon105126
Post 3

I have clawed a chalkboard before and I will never, ever do it again. It was awful!

anon104731
Post 2

I don't even need to hear it, all I need is to think about it and the hair on the back of my neck stands and I get a shiver down my spine.

anon104577
Post 1

My ears started hurting while I read this article!

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