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68 HAND-BOOK OF ACOUSTICS. |
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A Resonator is an open vessel of glass, metal, cardboard, or other material, of such dimensions, that the mass of air contained in it resounds to a note of a certain pitch. Its use is, to assist the ear in discriminating a sound of this particular pitch, from a number of others at different pitches, all sounding simultaneously.
In order that a column of air, in a cylindrical tube open at both ends, may vibrate in unison with a given sound, the length of the tube must be approximately one half the length of the corresponding sound wave.
If the tube be closed at one end, its length must be one-fourth that of the sound wave.
In both cases the diameter of the tube should not exceed one-sixth the length. |
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