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Science

Why Fingernails On a Chalkboard Sound Painful 176

Posted by Soulskill from the enjoy-your-goosebumps dept.
sciencehabit writes "Some sounds are excruciating. Take fingernails squeaking on a chalkboard. The noise makes many people shudder, but researchers never knew exactly why. A new study finds that there are two factors at work: the knowledge of where the sound is coming from and the unfortunate design of our ear canals. 'The offending frequencies were in the range of 2000 to 4000 Hz. Removing those made the sounds much easier to listen to. Deleting the tonal parts of the sound entirely also made listeners perceive the sound as more pleasant, whereas removing other frequencies or the noisy, scraping parts of the sound made little difference.'"
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Why Fingernails On a Chalkboard Sound Painful More

Why Fingernails On a Chalkboard Sound Painful

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  • Taught? (Score:3, Interesting)

    by Hazel Bergeron ( 2015538 ) on Monday October 31, 2011 @04:08PM (#37899466) Journal

    Did they test with people who haven't been culturally informed that fingernails on a chalkboard should sound annoying?

    From chalk to communism, there are so many, "Why do people find blah disagreeable?" which seem to come down to, "Because that's what mother and the TV say."

    • Re:Taught? (Score:5, Insightful)

      by decipher_saint ( 72686 ) on Monday October 31, 2011 @04:14PM (#37899544)

      Dammit no. I remember being a child and hearing that sound and cringing then finding out AFTER that I wasn't alone.

      Some things just plain old suck (like fingernails on a chalkboard and communism).

      • I never found it to be that annoying.

        Now, silverware scratching on a plate? Gives me the shudders.

        • Re: (Score:2)

          by Kagura ( 843695 )

          I never found it to be that annoying.

          Now, silverware scratching on a plate? Gives me the shudders.

          Exactly the same for me! "Fingernails on a chalkboard" kinds of sounds never bothered me in the slightest. But if I'm the one scraping silverware on a plate, it makes me shudder exactly like other people do when hearing fingernails on a chalkboard! It's weird, maybe my sense of whatever causes the shuddering is slightly "shifted" compared to a normal person.

        • Re: (Score:2)

          by Mal-2 ( 675116 )

          I never found it to be that annoying.

          Now, silverware scratching on a plate? Gives me the shudders.

          Stravinsky was at a formal dinner of some sort, and asked the diner next to him "do you know how to make a violin section do this?" and scraped his fork across his plate with a horrible screech. When the fellow diner cringed, Stravinsky smiled, and said "I do."

      • Communism, like Capitalism: I am not actually aware of anywhere which have attempted to implement these pure concepts.
        Everywhere tends to end up implementing an ad-hoc mish-mash of all three... in varying degrees and proportions.

        • To go completely off-topic:
          Places that historically have been capitalism-based have tended to be generally quite free, and prosperous. Places that have shot for communism have tended to end up as authoritarian, murderous nightmares. The one possible counter-example I can think of, is what China may look like in 20 years-- and mostly because they are shedding so much of the communist vestiges and aiming at hyper-capitalism right now (though they are retaining the authoritarian nature).

          Take that how you wan

          • True, but have you considered reverse causation? 'Places whose culture is of authoritarian murderous nightmares tend to end up with extreme political systems'. Communism is indeed one of those, but think also Mexico, Cambodia, Burma, Saudi...

            • Why dont we look at Russia / Soviet Union / USSR over the past 100 years, and tell me whether it got better or worse (in terms of "millions of people murdered") after the introduction of communism?

        • Re: (Score:2)

          by hitmark ( 640295 )

          Iraq is the most recent attempt at getting pure capitalism shocked into existence. So far failed attempts are Argentina, Peru and Russia.

    • Re: (Score:2)

      by JigJag ( 2046772 )

      I agree with you. Fingernails on chalkboard never bothered me and they still don't. I have excellent audio reception btw so it's not a question of being tone-deaf. I hear the sounds but my skin doesn't crawl up.

      On a related note, I moved from a place with no skunks to a place teeming with them. To the locals, the odour is unbearable and they have like a flight-response to it. Personally, I don't abhor the smell; It's akin to "burning rubber". When my mother visited, it reminded her of the smell of "roasting

      • On a related note, I moved from a place with no skunks to a place teeming with them. To the locals, the odour is unbearable and they have like a flight-response to it.

        I have seen another distinct entry for your list of reactions. Potheads apparently love the smell. As a non-pothead who grew up in skunk country, it's pretty funny to see people who can't get enough of that vile aroma. Gross!

      • Perhaps the odor varies from location to location due to diet or other envrionmental conditions, and possibly by the distance from the point of origin. You should thus perform an experiment for our edification:
        1. Acquire the appropriate eye protection and a sufficient supply of clothing to replace the ruined clothing you will be burning.
        2. Travel to each state and province in North America where skunks are naturally found. Optionally, include locations on other continents.
        3. Start at a distance of 100m from the

      • Re:Taught? (Score:4, Interesting)

        by bws111 ( 1216812 ) on Monday October 31, 2011 @04:43PM (#37899976)

        Isn't that just learning? You have not yet directly experienced skunk spray, so it doesn't have the same effect on you as someone who has experienced it. The area I have always lived in has a lot of skunks. Like you, the smell never bothered me all that much. Then one day our cat got sprayed, and before we knew it he was in the house. Now I absolutely can not stand that smell, no matter how far off it is.

        • Isn't that just learning? You have not yet directly experienced skunk spray, so it doesn't have the same effect on you as someone who has experienced it. The area I have always lived in has a lot of skunks. Like you, the smell never bothered me all that much. Then one day our cat got sprayed, and before we knew it he was in the house. Now I absolutely can not stand that smell, no matter how far off it is.

          People who've never lived in areas with a lot of skunks seldom appreciate just how potent and horrendous

          • This. One time a skunk sprayed underneath the cabin my family was staying in. It was in the middle of the night, and woke all of us up. We searched the whole place, afraid an appliance was burning out or something It was an awful chemical plastic burning smell that was nothing like the "skunky" whiff you get passing one on the road.

      • Re: (Score:3)

        by anagama ( 611277 )

        I have this great book of marine charts for the Puget Sound which places historical anecdotes in place context.

        There is one entry from early European explorers, which indicates that one of the men chased down a skunk having never seen such an animal before. It continues to note that the stench was unbearable, that no amount of boiling would remove it from the clothes, and that in the end, the skunk hunters were forced to destroy their clothing.

        I'd quote it exactly but its on my boat. Anyway, close contact

    • Re: (Score:3)

      by skids ( 119237 )

      More importantly, do they control for whether or not test subjects have actually tried to make the noise by themselves running their fingernails down a chalkboard.

      For me the noise meant nothing until it was linked with the disturbing feeling of chalk building up under my nails as they vibrate painfully.

      • Re: (Score:2)

        by bws111 ( 1216812 )

        I was thinking the same thing. The noise itself does not bother me, but the thought of my own fingernails doing that gives me the creeps.

      • You get the same effect when you scrape a knife/fork the wrong way on a plate when eating. Surely this should be control enough, as it's a similar painful sound, without the pain associated with physical discomfort?

    • FTFA:

      The ratings also changed depending on what the listeners thought the sounds were. If they thought a sound came from a musical composition, they rated it as less unpleasant than if they knew it actually was fingernails on a chalkboard. But their skin conductivity changed consistently even when they thought the chalkboard sound was from music and rated it as less unpleasant.

      So yes. They discovered that, even when people said they didn't find it as unpleasant (and thought it was supposed to be music), there was still a physical pain-like reaction in the hearers. Some sounds really are painful.

      Of course, I would probably find it even more painful if you told me it was from a modern musical composition. Cannot stand that crap (I'm talking the orchestral-style musical crap, not the Britney Spears-style musical crap.)

    • Some listeners were told the true source of the sounds, whereas others were told that the sounds were part of contemporary musical compositions.

      The ratings also changed depending on what the listeners thought the sounds were. If they thought a sound came from a musical composition, they rated it as less unpleasant than if they knew it actually was fingernails on a chalkboard. But their skin conductivity changed consistently even when they thought the chalkboard sound was from music and rated it as less unpleasant.

      So naw.. that theory doesn't really hold much water. Personally, I found the chalkboard sound unbearable well before I "knew" I was meant to. More likely it's simply that some folk don't react the same way to that sound (and likely, have their own quirks, completely unrelated). There's a physiological explanation for this which doesn't involve influence, like how some people absolutely can't stand the flavour of gherkin (or pickle, if you prefer), and some love it so much they'll eat my discarded gherkin sl

      • Also, apologies, I did mean to highlight the second part of that, where their skin consistency changed consistently in either scenario. The part I highlighted agrees with what you said - that there is a cultural attitude that fingernails on a chalkboard is an unpleasant sound. However, this seems to not have any effect on the physiological reaction - that being, the physical reaction is the same in either case.

    • My cats don't like sounds like that either and I never taught them about the evils of communism.

      Seriously, who modded that up? Somebody who went to a school where the teacher said "Okay class, here's something else you shouldn't like..."

    • Re: (Score:2)

      by falzer ( 224563 )

      It would get very tiresome for everyone to have to explain from axioms and first principles every opinion they held, even if they did reflect upon and study them.
      Alternately, do you think people who agree with you on whatever subject have also been "culturally informed" that way?

      I am, of course, not talking about capitalism, communism, chalk, or cottonballs, but wearing socks with sandals.

      • Re: (Score:2)

        by richlv ( 778496 )

        oooh. people who object to others wearing socks should be forced to obey any whims anybody on the planet might have. the desire to inflict upon others the annoying feeling of sweaty feet just requires some pushback :>

  • Just thinking about it (Score:5, Interesting)

    by mrxak ( 727974 ) on Monday October 31, 2011 @04:10PM (#37899488)

    There's certainly a psychological component. Just thinking about that noise and making the clawing/scraping motion with my hand, right now, made me react as I would hearing it for real.

    • Shit, me too. Stop it.

    • Re:Just thinking about it (Score:4, Funny)

      by Baloroth ( 2370816 ) on Monday October 31, 2011 @04:27PM (#37899726)
      They also tested Styrofoam squeaks and forks scraping on plates. You are welcome :)

      • Re: (Score:2)

        by mrxak ( 727974 )

        Fork-scraping never bothered me. Maybe it depends on the fork and plate, but as I recall, it's usually lower frequency. Styrofoam is annoying, but not shiver-inducing like the fingernails on chalkboard thing. Again, I think the frequency is lower most of the time I've encountered the stuff rubbing against itself.

        • Re: (Score:2)

          by Mal-2 ( 675116 )

          Fork-scraping never bothered me. Maybe it depends on the fork and plate, but as I recall, it's usually lower frequency. Styrofoam is annoying, but not shiver-inducing like the fingernails on chalkboard thing. Again, I think the frequency is lower most of the time I've encountered the stuff rubbing against itself.

          My parakeet rather likes squeaky noises made by rubbing styrofoam against various things. This sound can actually get her to start singing or playing with bells. She also likes when I watch basketball, because of the squeaky shoes.

        • Re: (Score:2)

          by hitmark ( 640295 )

          I would say it heavily depends on the plate, or more accurately its glazing. We have a older set in the house that makes a annoying noise if there is the slightest angled contact between the plate and fork.

        • Meh. I think the article is a bit shallow when talking about "frequency" being the only characteristic of sound. Does a bare high-frequency sine give you the same chills than the chalkboard or plate thing. Not to me. So there's more to it, and I would think the biggest factor of it is knowing or/and seeing where the sound comes from.

  • Since it's a range of doubling frequency, it's one octave. Worst. Scale. Ever.

  • You can employ these sounds in your Halloween display!!!

    "I just had that horrible feeling I was in 4th period English again and didn't have my book report done! Arrrggghhh!"

  • They still haven't explained it (Score:4, Insightful)

    by Arlet ( 29997 ) on Monday October 31, 2011 @04:14PM (#37899548)

    They've only narrowed down the class of sounds, but not why we would find those sounds so annoying.

    • The researchers suspect that the shape of the human ear canal may be to blame for the pain. Previous studies have shown that the ear canal amplifies certain frequencies, including those in the range of 2000 to 4000 Hz. A loud screech on a chalkboard could be amplified within our ears to painful effect, the researchers propose.

      So, in a sense they did. They didn't prove this is why it is annoying, but it is definitely a possible (and likely) explanation. I personally have noticed those noises appear extremely loud (and hence very annoying.) This may also explain why some people don't find it quite as annoying (as some comments above note): minor variation in ear canal shape would amplify different specific ranges, so certain frequencies could annoy different people more.

    • They've only narrowed down the class of sounds, but not why we would find those sounds so annoying.

      Some video I watched in high school bio class said that the sounds are coincidentally almost the same waveform as primate danger screeches. Hard-wired aversion.

      Seems plausible.

  • The Straight Dope ...did it (Score:5, Informative)

    by smoothnorman ( 1670542 ) on Monday October 31, 2011 @04:22PM (#37899658)
    and in 1986 no less (back when "chalkboard" still had some meaning): http://www.straightdope.com/columns/read/540/why-is-the-sound-of-fingernails-scraping-a-blackboard-so-annoying [straightdope.com]

    • We still have chalkboards?

      I thought everybody was getting high off those markers? How about why do those give me headaches?

      • Re: (Score:2)

        by rossdee ( 243626 )

        When I was a lad at school the teacher would write on a blackboard with chalk. I assume this is refered to these days as a chalkboard - maybe the term blackboard is politically incorrect.

        (I am sure that they would not be allowed to throw chalk at the children who were misbehaving either these days)

      • In mathematics departments (in the US, that I know of), there is not a trend toward whiteboards. We like chalk, and are constantly at odds with our IT people who complain about dust in the computers.

        We never asked for the computers, either.

      • The markers give you headaches because they contain a solvent, which is included to make it easier to clean the boards. They're generally based on organic compounds with a low boiling point, so they evaporate quickly, leading to high levels of fumes in the area. When you inhale the fumes they irritate your mucus membranes, leading to a variety of symptoms, including headaches.

    • They quote some research which compared two sounds, found them similar, and concluded one was the cause of the other.

      I used to like this idea, but after reading this again it's bunk. They have a hypothesis but nothing to back it up. I like the ear canal idea better, and that leads us the other way around.

      In conclusion, monkey shrieks evolved to match our ear canal design because those who were able to warn others were part of a successful coping strategy. And chalkboards just by chance happen to be simil

    • Re: (Score:2)

      by Timmmm ( 636430 )

      Erm, blackboards are still used...

      Also, why do neither of these articles have the sounds to listen to? Seriously, this is as bad as all those articles about imaging that don't have pictures...

  • It is because it makes me feel as if im doing it, which is very irritating. that dusty blackboard, the nails going against it in the opposite direction.

    notice, the feeling is not so irritating if you do it in the right direction - outwards.

  • That's Baby Crying Frequency (Score:5, Interesting)

    by Sarusa ( 104047 ) on Monday October 31, 2011 @04:41PM (#37899950)

    Baby crying has a wide variation, and the fundamental frequency is (depending on who you ask) somewhere around 500Hz, but you get strong harmonics and nonlinears up in the 3Khz area. The non-linears are a strong part of the annoyance too. See for example http://ergo.human.cornell.edu/studentdownloads/DEA3500pdfs/hearing.pdf [cornell.edu]

    And you are designed by millions of years of evolution to find that so annoying you will do anything to make it stop.

    • There is also the fact that our direction sensing of sound is most sensitive at 2.5KHZ, which also is one of the frequencies
      that we hear very efficiently, I have seen it suggeted due to that region being common in the rustling of leaves and breaking twigs, it was a great asset when avoiding predators in the wild, so we evolved suck sensitivity.

      So much so that Robbie McGrath, AC/DC and Simply Red sound engineer once wrote "2.5K is volume"

    • Re: (Score:2)

      by Geminii ( 954348 )
      "You have: a hammer..."

    • "And you are designed by millions of years of evolution ..."

      A great example of some of the difficulties of stating evolutionary theory fairly. You can't say that evolution "designed" something, because evolution is a response to external conditions that affect reproduction. It is a weeding-out process. Thus, you'd have to say something like, "Over millions of years of evolution, some external sound source, whose effect on people whose sensitivity to sound was either narrower or broader than today, and wh

  • needles into styrofoam. Ugh, makes me cringe just thinking about it.

  • Worse than fingernails (Score:3, Interesting)

    by Anonymous Coward on Monday October 31, 2011 @05:03PM (#37900238)

    My high school music teacher taught me how to make a stick of chalk squeal on a chalkboard at will.

    Hold a fresh piece between your first two fingers and your thumb lightly, with the other end resting against the middle of your palm. hold the tip against the board with a sharp downward angle about the same as a backslash \, and draw a line downward. Don't press too hard or you'll dampen the resonance and get nothing. When you get the hang of it it's very easy to produce a head-splitting screech above 100dB

  • Fingernails raking against a chalkboard and chalk squeaking against slate were the most unpleasant sounds from a family of recordings, which also included sounds such as Styrofoam squeaks and scraping a plate with a fork.

    Oh scraping a plate with a fork.. *shudder*

    Also unpleasant: rub the smooth ends of two drills together.

    But I have to give kudos to Shad Clark for a sound that is not necessarily cringe-worthy on its own - but by virtue of its associated visual, makes the hairs on my arms stand on end just t

  • A little late on this one (Score:4, Funny)

    by dontmakemethink ( 1186169 ) on Monday October 31, 2011 @05:55PM (#37900868)

    You don't need an audiology experiment to figure this out. Harvey Fletcher and W. A. Munson established the lab work back in 1933, resulting in the Fletcher-Munson Curve [slashdot.org] which illustrates how the sensitivity of the human ear varies at different frequency ranges and volume levels, and is most sensitive in the 2-6kHz range. It's fair to assume this range is more sensitive since it is the hardest range for predators to keep silent while stalking prey, i.e. a twig snapping.

    It is believed mankind has pre-historic rodents to thank for their advanced auditory system, which developed during the 65 million year period where mammals and dinosaurs co-existed. During this time there was low oxygen content in the air, so mammals had to maintain high respiratory rates, making them easy prey for the much larger dinosaurs, whose respiratory system involved hollow bones to transport air directly throughout their bodies rather than just lungs to deliver oxygen to the bloodstream. (Birds benefited from the hollow bones to fly, but only use lungs for respiration now that oxygen levels are up.) Mammals had to forage at night and depended almost entirely on their auditory systems for defense. 65 million years of that is likely the only reason we can discern music, much less appreciate it.

    As a sound engineer I can attest that the 2-6kHz range is of special significance when putting a mix together. It's usually actually more important that the 2-6kHz range of each voice or instrument be balanced against each other than each voice or instrument be of even frequency response themselves. If something is dominant in that range, it dominates the listener's attention every time. If something has a sharp spike in that range, meaning a very narrow frequency band, it will not be pleasant to the ear. If you check out the frequency response graphs of the cheaper guitar speakers by clicking on the options here [usspeaker.com], you might notice they all have spikes around 2-2.5kHz. That is why they suck.

    • Beat me to it! Quite right about the predators. I remember years ago Robbie McGrath AC/DC sound guy wrote in sonics magazine;

      250HZ is mud, 2.5KHZ is volume.

  • In a physics class I asked the instructor is there something in our brain that resonates from chalkboard squeals? He thought probably so, kind of like that Tacoma bridge incident. A math teacher used to get excited when the boards were cleaned by custodian, "Yes! We can now break this in" as he would grab a new piece of chalk to use on that dark green board. Then there were some erasers extra wide so not take too long to wipe the board. What about a pocket defense system that blasts high dB levels of this c

    • I find it interesting that you think 20 year olds don't know what a chalk board is. I'm 27 and currently going to a university in which I have not seen a single dry-erase board. Also, my high school was about 75% chalk and 25% marker.

    • The pocket defense system you speak of already exists, more or less, in the form of rape alarms (not quite debilitating but certainly annoying) and the serious "sound grenade).
  • I can't hear the sound of fingernails on a chalkboard. And no, its not because whiteboards are so much more common now. It's also not from too many loud concerts or anything like that; I couldn't hear fingernails on a chalkboard when I was in elementary school, either (I did it once to get my classmates' attention and thought I was doing it wrong since I didn't hear anything).

    Are there many others who can't hear it?

  • As a kid nothing could phase me. I'd laugh when someone would try it and I'd see everyone freaking out. But when I turned around 20 several years ago that all changed and I've become super sensitive. It's not even just fingernails on chalk boards that get me, it's a wide assortment of things.

  • .

    Ah, yes. Very familiar with that range.

    The "Ex-Wife" frequencies.

    .

  • I can not remember which Science Show I was watching at the time but I learned that it was the lower frequencies at least in the early 2000's.

    While I'm not sure if they mentioned the specific 2k-4k range, they had broken the noise into low, mid, and high frequencies and did a test with people listening to the noise. While some did flinch at the higher frequencies, most reacted to the lower range.

    So unless they took almost a decade to isolate the specific frequency range...is this really new?

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