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Q & A: whispering gallery

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Most recent answer: 10/22/2007
Q:
I am always listening about the saint’s paul whispering gallery. COuld you explain a lit bit more about this effect? Thank you,
- Tom (age 14)
Saint John Collede, London
A:
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.

mike w.

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.

Tom

(published on 10/22/2007)

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