|MadSci Network: Physics|
Sometimes it is possible to excite the natural frequencies of a particular object or space. One favorite way is to apply sound waves at the frequecy that the object or space would respond to. The natural frequency of an object has a lot to do with the material it is made of and its shape. This phenomenon is most obvious with tuning forks, but buildings, rooms, the sun and many other objects also have natural frequencies at which they will tend to vibrate. For a room, these frequencies will tend to be low, but still within the range of the human ear. A good way to get at the natural frequency of a space is to compare the wavelength of the note in air with the dimensions of the space. A low "G" note has a wavelength of about 7 feet. Higher frequencies have shorter wavelengths, and would not resonate with a large space. Even lower frequencies need larger spaces to resonate, but a room is a conveniently lower-register sized space.
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