science

Whispering gallery

Whispering gallery is a science topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Whispering gallery rather than just read about it. In short: A whispering gallery is usually a circular, hemispherical, elliptical or ellipsoidal enclosure, often beneath a dome or a vault, in which whispers can be heard clearly in other parts of the gallery. Such galleries can also be set up using two parabolic dishes.

Key takeaways

Whispering gallery belongs to science; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Whispering gallery to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Whispering gallery from memory before moving on to harder problems.

Reference excerpt

A whispering gallery is usually a circular, hemispherical, elliptical or ellipsoidal enclosure, often beneath a dome or a vault, in which whispers can be heard clearly in other parts of the gallery. Such galleries can also be set up using two parabolic dishes. Sometimes the phenomenon is detected in caves.

Theory A whispering gallery is most simply constructed in the form of a circular wall, and allows whispered communication from any part of the internal side of the circumference to any other part. The sound is carried by waves, known as whispering-gallery waves, that travel around the circumference clinging to the walls, an effect that was discovered in the whispering gallery of St Paul's Cathedral in London. The extent to which the sound travels at St Paul's can also be judged by clapping in the gallery, which produces four echoes. Other historical examples are the Gol Gumbaz mausoleum in Bijapur, India and the Echo Wall of the Temple of Heaven in Beijing. A hemispherical enclosure will also guide whispering gallery waves. 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, with an accessible point at each focus. In this case, when a visitor stands at one focus and whispers, the line of sound emanating from this focus reflects directly to the focus at the other end of the gallery, where the whispers may be heard. 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. Egg-shaped galleries, such as the Golghar Granary at Bankipore, and irregularly shaped smooth-walled galleries in the form of caves, such as the Ear of Dionysius in Syracuse, also exist.

Examples

India The Gol Gumbaz in Bijapur, India. The Golghar Granary in Bankipore, India. The Victoria Memorial in Kolkata.

United Kingdom St Paul's Cathedral in London is the place where whispering-gallery waves were first discovered by Lord Rayleigh c. 1878. Gloucester Cathedral has a whispering gallery. The Berkeley Wetherspoons Bristol has a whispering gallery.

United States Grand Central Terminal in New York City: a landing amid the Oyster Bar ramps, in front of the Oyster Bar restaurant Statuary Hall in the United States Capitol. Salt Lake Tabernacle in Salt Lake City, Utah Centennial fountain in front of Green Library at Stanford University in California Gates Circle, Buffalo, New York The Whispering Arch in St. Louis Union Station Charles Stover Bench, Central Park, New York, New York Waldo Hutchins Bench, Central Park, New York, New York Whispering Gallery, Museum of Science and Industry (Chicago)

Other parts of the world The Echo Wall in the Temple of Heaven in Beijing. Basilica of St. John Lateran, Rome. The Salle des Caryatides in the Louvre, Paris, France. Ear of Dionysius cave in Syracuse, Sicily. Palazzo del Podestà, Bologna, Italy. Banco dos Namorados (Lovers' bench) in Santiago de Compostela, Spain.

In science The term whispering gallery has been borrowed in the physical sciences to describe other forms of whispering-gallery waves such as light or matter waves.

See also Acoustic mirror Parabolic loudspeaker Room acoustics

References

External links

Ear of Dionysius: visiting information, videos and sounds of this cave. Grand Central Station: visiting information, videos and sounds of the whispering gallery. St Paul's Cathedral: visiting information, videos and sounds of the whispering gallery.

Illustrations

Worked examples

Example 1 — a first encounter with Whispering gallery

Start with the simplest possible case. Write down what Whispering gallery claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Whispering gallery before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Whispering gallery ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Whispering gallery

In research: Whispering gallery appears in science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Whispering gallery in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Whispering gallery is common in secondary-school and first-year university syllabi. It links to neighbouring topics Acoustics, Rooms, so understanding it makes those chapters shorter.
In everyday life: Look for Whispering gallery outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Whispering gallery in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Whispering gallery means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Whispering gallery out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Whispering gallery in simple terms?

Why does Whispering gallery matter?

Because it connects several science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Whispering gallery?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Whispering gallery.