A whispering gallery is usually a circular, hemispherical, elliptical, or ellipsoidal enclosure, beneath a dome or a vault, in which whispers can be heard clearly in other parts of the gallery. There are two famous whispering galleries - Grand Central Terminal and St. Paul's Cathedral in London. In these two galleries, the faintest whispers can be heard clearly due to the geometry of the room. So, one should be careful about what they speak.
It is called a whispering gallery because of the sound waves carried under them which are known as whispering gallery waves. These waves travel around the circumference, sticking to the walls. It works on the principle of how sound waves bounce around the inside of this curving section of hard wall.
St.Paul's Cathedral in London was the first whispering gallery. Lord Rayleigh discovered whispering gallery waves for the first time in there. He experimented in the 1870s with a wedding ring and found that that the sound waves creep horizontally against the walls by the process of reflection. He realized that the circular shape allows the sound waves to bounce on the walls multiple times at different angles. Due to multiple reflections, the whisper is heard exactly on the opposite side.
Credits: Harini
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