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Why Fingernails On a Chalkboard Sound Painful

Posted by Soulskill on 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.'"

5 of 176 comments (clear)

  1. Taught? by Hazel+Bergeron · · Score: 2, Interesting

    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."

    1. Re:Taught? by bws111 · · Score: 3, Interesting

      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.

  2. Just thinking about it by mrxak · · Score: 4, Interesting

    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.

    --
    -mrxak
    Onions Will Kill You
  3. That's Baby Crying Frequency by Sarusa · · Score: 4, Interesting

    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

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

  4. Worse than fingernails by Anonymous Coward · · Score: 3, Interesting

    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