Glass Blackboard
3 June 2010
Glass Blackboard
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Re: the phrase 'setting my teeth on edge' why does the scratch of a nail on glass causes a teeth sensation?
In the days of old-fashioned blackboards a little impurity in chalk screeching on the board would cause nearly all kids to cringe. Why is the sensation felt in the area of the teeth (particularly upper teeth)?
It's due to the frequency of the sound. It sets up a resonance from the cochlea and is transmitted through the nerves into the teeth.
