Squeaky blackboards

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The squeaking of wall panels is a noise which by scratching a writing board , such as is used in schools, for example, nails , or by school chalk is caused on tablets. The noise is physically caused by the sticky slip effect , in which the school chalk or other objects drawn over the blackboard get stuck on microscopic bumps and start to vibrate . The noise that is made when scratching the blackboard is generally perceived as extremely unpleasant. This squeak is the subject of scientific research. In 2006, Lynn Halpern, Randolph Blake and James Hillenbrand were awarded the Ig Nobel Prize in the acoustics category for a study on why scratching blackboards with fingernails is uncomfortable .

Theories

In several studies, science has dealt with the question of why the sound of scratching the blackboard is perceived as unpleasant. There are several approaches to this.

Neurobiological Approach

After an examination with a magnetic resonance tomograph , a study came to the conclusion that the frequencies produced between 2000 and 5000 Hertz lead to negative reactions in the amygdala . However, other studies come to the conclusion that rather medium frequencies cause the unpleasant feelings.

Experience-based approach

Another approach assumes negative experiences as the reason for the rejection of the noise. In an experiment, the origin of the noise was explained to a group beforehand. The comparison group was told it was modern music. The comparison group showed significantly fewer negative reactions. It was concluded from this that personal experiences and expectations were decisive.

Footnotes

  1. ↑ Why is chalk squeaking on the blackboard? , Geo
  2. ↑ The Weirdest Findings in Music Research - VICE. Retrieved January 22, 2020 .
  3. ^ Winners of the Ig® Nobel Prize. Retrieved January 22, 2020 .
  4. ↑ Nadja Podbregar: Neurology: Why squeaky chalk makes us shudder . In: THE WORLD . October 15, 2012 ( welt.de [accessed January 22, 2020]).
  5. ↑ a b Berliner Morgenpost- Berlin: Quieeeeeeeetsch! February 28, 2012, accessed on January 22, 2020 (German).

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