The Whispering Gallery at St Paul’s Cathedral in London

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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."

St Paul’s Cathedral is the Anglican Cathedral on Ludgate Hill, in the City of London and dates from the 17th century. The Whispering Gallery’s name comes from the fact that a whisper whispered by a person facing the wall on one side, can clearly be heard by a listener with an ear held at any other point to the wall around the gallery. This doesn’t work for normal voiced speech but only for whispered speech.

“The prevailing theory behind why whispering galleries work (first proposed in 1871 by British astronomer George Airy to explain St. Paul’s cathedral) is that sound originating at one point along the circumference of an enclosed sphere is reflected to another point along the circumference opposite the source.”

According to experts, a whisper directed tangentially to the surface is clearly heard on the other side of the gallery because the whisperer’s voice follows the curve of the domed ceiling. This phenomenon is especially assisted by the fact that the walls are dome-shaped because this means that instead of the upward-directed components of the whispered sounds being lost above, it rather tends to be reflected downwards and is conserved. The late Lord Rayleigh (1904) explained that the acoustical effects observed are due to the curvilinear propagation of sound and the waves which “proceed from a source placed close to the wall of the gallery clinging to its surface and creeping tangentially along it”. He stated that the effects were not due to the sound being a reflection of the dome overhead but rather to a waveguide effect.

The rea...

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