Whispering gallery

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A whispering gallery " is a gallery beneath a dome or vault or enclosed in a circular or elliptical area in which whispers can be heard clearly in other parts of the building.

A whispering gallery is usually constructed in the form of an ellipsoid, with an accessible point at each focus. When a visitor stands at one focus and whispers, the line of sound emanating from this focus reflects directly to the dish/focus at the other end of the room, and to the other person. Circular whispering galleries may provide "communication" from any part on the circumference to the diametrically-opposite point on the circumference.

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[edit] Examples

Whispering galleries also occur naturally in the ocean. Instead of the reflecting surface it is the sound rays that are curved and the reflecting 'wall' (the sea surface) is flat.[2] The same phenomenon occurs for radio waves propagating in the atmosphere.[3]

Caltech in the US has been doing research on optical whispering galleries, which so far are no bigger than 40 micrometres in diameter, and must be filtered to be seen.

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[edit] References

  1. ^ A. E. Bate, Note on the whispering gallery of St Paul's Cathedral, London. Proceedings of the Physical Society, 50:293–297, 1938.
  2. ^ D. E. Weston, Guided acoustic waves in the ocean. Reports on Progress in Physics, 42:347–387, 1979.
  3. ^ K. G. Budden & H. G. Martin, The Ionosphere as a Whispering Gallery. Proceedings of the Royal Society of London. Series A, Mathematical and Physical Sciences, 265(No. 1323):554–569, 1962.

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