Whispering gallery

[1] The extent to which the sound travels at St Paul's can also be judged by clapping in the gallery, which produces four echoes.

[2] Other historical examples[3][4][5] are the Gol Gumbaz mausoleum in Bijapur, India and the Echo Wall of the Temple of Heaven in Beijing.

The waves carry the words so that others will be able to hear them from the opposite side of the gallery.

The gallery may also be in the form of an ellipse or ellipsoid,[4] with an accessible point at each focus.

In a similar way, two large concave parabolic dishes, serving as acoustic mirrors, may be erected facing each other in a room or outdoors to serve as a whispering gallery, a common feature of science museums.