November 6, 2011
What Makes Fingernails On A Chalkboard So Annoying?
New research presented during last week's annual conference of the Acoustical Society of America has helped to shed some light on why the sound of fingernails on a chalkboard is such an extreme irritant to so many people.
The infamous screeching sound, to which many unpleasant things are often compared, bothers people so much because of the shape of their inner year, Michael Oehler of the Macromedia University for Media and Communication in Cologne, Germany and colleague have discovered.
They presented their findings during the 162nd Meeting of the Acoustical Society of America, held from October 31 through November 4 in San Diego, California.
In an article describing the research, Rob Waugh of the Daily Mail writes that the human ear is "built" to hear sounds at that frequency, which is similar to ordinary speech.
"The researchers used a test where some listeners thought they were listening to 'difficult' experimental music, and others were told they were listening to various horrible sounds," Waugh reported on Friday.
"Nails on a blackboard ranked above sounds such as a fork scraping on a plate and squeaking polystyrene," he added, noting that "listeners who'd been told they were listening to fingernails were more disgusted and appalled than those who hadn't."
According to a CBS News article written by WebMD's Jennifer Warner, fingernails scratching on a blackboard produce high-pitched noises in the range of 2000 and 4000 hertz. Because the ear canal amplifies sounds at these frequencies, Warner says, the human ear is especially sensitive to these types of sounds and they literally become louder to us.
In addition to measuring the degree of pleasantness or unpleasantness of the sounds they were listening to, Warner adds that Oehler and his colleague measured their blood pressure, heart rate, and level of perspiration.
She said that the researchers discovered that those who knew they were listening to fingernails on a chalkboard had a "stronger stress response, in particular sweating, than those who thought they were listening to music."
The results have not yet been peer reviewed or published in a scientific journal.
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