By Duncan Geere, Wired UK
Much time has been spent, over the past century, on working out exactly what it is about the sound of fingernails on a blackboard that’s so unpleasant. A new study pins the blame on psychology and the design of our ear canals.
Previous research on the subject suggested that the sound is acoustically similar to the warning call of a primate, but that theory was debunked after monkeys responded to amplitude-matched white noise and other high-pitched sounds, whereas humans did not. Another study, in 1986, manipulated a recording of blackboard scraping and found that the medium-pitched frequencies are the source of the adverse reaction, rather than the the higher pitches (as previously thought). The work won author Randolph Blake an Ig Nobel Prize in 2006.
The latest study, conducted by musicologists Michael Oehler of the Macromedia University for Media and Communication in Cologne, Germany, and Christoph Reuter of the University of Vienna, looked at other sounds that generate a similar reaction — including chalk on slate, styrofoam squeaks, a plate being scraped by a fork, and the ol’ fingernails on blackboard.
Some participants were told the genuine source of the sound, and others were told that the sounds were part of a contemporary music composition. Researchers asked the participants to rank which were the worst, and also monitored physical indicators of distress — heart rate, blood pressure and the electrical conductivity of skin.
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