Science Questions

Why does the sound of nails on a chalkboard bother us so much?

Sun, 10th Jan 2010

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Question

Saeema asked:

Hi, I'm a 16 year old student in Canada and I'd like to know why it irritates us when nails go down a chalkboard, or squeaky sounds in general.

Answer

Chris - The only, and the best, explanation I've heard of this is that the frequency distribution that’s emitted by the nails going down the chalkboard is very reminiscent, at very high frequencies, of distress sounds produced by other animals.  This plugs in to the primeval response in all of us of an animal in distress.  For this reason, we experience this sound with an “Ouch!  I don't like it!  I have to wake up and take notice!” reaction.

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Saeema S asked the Naked Scientists: Hi, I'm a 16 year old student in Canada and I'd like to know why it irritates us when nails go down a chalkboard, or squeaky sounds in general. Thanks, Saeema What do you think? Saeema S , Sun, 29th Nov 2009

http://www.thenakedscientists.com/forum/index.php?topic=1464.msg12609#msg12609


Personally I don't agree with the "screaming monkey" hypothesis ...
http://www.thenakedscientists.com/forum/index.php?topic=14996.0


Another hypothesis …

The squeak which triggers the response can be produced by teeth biting bone.

Perhaps the reflex has come about to prevent carnivores from damaging their teeth on bones.


RD, Sun, 29th Nov 2009

First thing to point out is that it doesn't bother everyone to the same degree i.e. it doesn't bother me too much, so I'll go along with RD's scepticism re the screaming monkey hypothesis, although I will admit to finding it mildly irritating, if only because it is unaesthetic.

Having said that, it does seem to be a relatively primeval response though.  Actually, considering how much variation there is in the response now, I'd hazard a guess that it may pre-date monkeys(primates), and come from an even earlier period of evolution.  It might not even be biology based (just had a weird idea about what an earthquake might sound like with no buildings or other artificial structures rattling about). LeeE, Sun, 29th Nov 2009



That is quite interesting to think about. What do you think it would sound like? glovesforfoxes, Sun, 29th Nov 2009



No idea; it was just a weird thought. LeeE, Mon, 30th Nov 2009

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