Hi rai130,
What a great question! :)
http://faculty.washington.edu/chudler/news29.html
SOUNDS LIKE SCHOOL
"What? The sound of nails on the chalkboard isn't pleasant? Does it
make the hair on your head stand up and send chills down your spine?
Why is this?
Back in 1986, a few scientists were curious about why the sound of
fingernails on the chalkboard was so annoying. They did some research
and published a paper called "Psychoacoustics of a Chilling Sound" (in
Perception and Psychophysics, vol. 39, pages 77-80, 1986). In their
study, 24 adults were tested to see how they rated the pleasantness
and unpleasantness of certain sounds. The researchers duplicated the
sound of fingernails on a chalkboard by scraping a "True Value
Pacemaker" three-pronged garden tool over a slate surface.
Here are the sounds that the subjects ranked in order from the most
pleasant to the most annoying:
Chimes
Spinning bicycle tire
Running water
Jingling keys
Pure tone
Pencil sharpener
Shaking metal parts
White noise
Compressed air
Blender motor
Dragged stool
Metal drawer being opened
Scraping wood
Scraping metal
Rubbing styrofoam together
Scraping slate with garden tool (the fingernail/chalkboard sound)
Rubbing styrofoam together was almost as annoying as scraping the
slate. The researchers were surprised to find that when low
frequencies of the unpleasant scraping sound were removed ("filtered
out"), the unpleasantness of the sound was reduced. On the other hand,
when the high frequencies of the unpleasant scraping sound were
filtered out, no effect was observed. For some reason, the low
frequency part of the scrape is what sends chills up your spine.
You may be thinking, "So what? Why should the sound of fingernails on
the chalkboard be so annoying?". No one really knows the answer to
this question. It is possible that there is some evolutionary
significance to this type of sound. Apparently, the nail/chalkboard
sound is very similar to the warning cry of some monkeys. The authors
of the "Chilling Sound" paper suggested that it is possible, just
possible, that the response to these annoying sounds is some
"leftover" reflex from a common primate ancestor. This reflex may be
built in to get our attention. It has even been suggested (in Medical
Hypothesis, vol. 46, page 487, 1996) that our response to this harsh
sound is a property of our inner ear leftover from a fish lateral line
system."
=========
Summary of "Psychoacoustics of a Chilling Sound"
http://www.mentalfloss.com/archives/archive2003-04-17.htm
=========
http://www.straightdope.com/classics/a2_317b.html
=========
http://www.amasci.com/amateur/screet.html
=========
Best regards,
tlspiegel |
