Why is the Sound of Fingernails on a Chalkboard so Irritating?

Michael Pollick
Michael Pollick

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.

A chalkboard.
A chalkboard.

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.

When the strings of a guitar are out of tune, the discordant results are noticeable.
When the strings of a guitar are out of tune, the discordant results are noticeable.

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.

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.

Michael Pollick
Michael Pollick

A regular wiseGEEK contributor, Michael enjoys doing research in order to satisfy his wide-ranging curiosity about a variety of arcane topics. Before becoming a professional writer, Michael worked as an English tutor, poet, voice-over artist, and DJ.

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Discussion Comments


I hate the sound of two latex balloons rubbing together, probably for the same reason I hate that blackboard sound. The other noise that bothers me is the sound of gym shoes squeaking on the floor during a basketball game. I think it has something to do with the randomness of the squeaks. It sounds like a hundred mice all squeaking at once to me.


"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.


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


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.


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.


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.


Some flash-bang stun grenades generate a similar sound.


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.


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


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.


My ears started hurting while I read this article!

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