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I am always listening about the saints paul whispering gallery. COuld you explain a lit bit more about this effect?
- Tom (age 14)
Saint John Collede, London
I guess the idea must be that the interesting shape of the dome in that
gallery is just right so that sound waves from one side take the same
length of time to travel to the other side regardless of which path
they take. In other words, sound is refocussed on the opposite side, by
a sort of sonic mirror. If I'd known about this I would have gone in
when I wandered through the St. Paul's courtyard a few weeks ago.
There's a similar effect with the U.S. Capitol rotunda which they
like to talk about on tours. Sound mirrors specifically built for the
purpose often work better than these accidental ones -- there's one at
the Exploratorium in San Francisco, for example, and they are a staple
of science museums.
(republished on 07/29/06)
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