tuning fork

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tuning fork,

steel instrument in the shape of a U with a short handle. When struck it produces an almost pure tone, retaining its pitch over a long period of time; thus it is a valuable aid in tuning musical instruments. It was invented in 1711 by John Shore, who jokingly called it a pitchfork.
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Tuning fork

A steel instrument consisting of two prongs and a handle which, when struck, emits a tone of fixed pitch. Because of their simple mechanical structure, purity of tone, and constant frequency, tuning forks are widely used as standards of frequency in musical acoustics. In its electrically driven form, a tuning fork serves to control electric circuits by producing frequency standards of high accuracy and stability. A tuning fork is essentially a transverse vibrator (see illustration). See Vibration

A tuning fork vibrating at its fundamental frequencyenlarge picture
A tuning fork vibrating at its fundamental frequency
McGraw-Hill Concise Encyclopedia of Physics. © 2002 by The McGraw-Hill Companies, Inc.
The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.

Tuning Fork


a source of sound, consisting of a metal rod that is bent and fixed in the center. The ends of the rod can vibrate freely. During the tuning of musical instruments, the tuning fork serves as the standard pitch of a tone; it is also used to give the pitch in singing. Forks that produce the tone A’ (A of the first octave) are usually used. Singers and choral conductors also use forks producing the tone C”. There are chromatic tuning forks, with prongs that have movable little weights. Depending on the position of these weights, the prongs vibrate at different frequencies.

The tuning fork was invented by the English musician J. Shore in 1711. At that time the standard frequency of vibrations for the tone A’ was 419.9 hertz (Hz). In the late 18th century the composer and conductor G. Sarti, who was working in St. Petersburg, introduced the “St. Petersburg tuning fork,” with an A’ = 436 Hz. In 1858 the Paris Academy of Sciences proposed a standard pitch tuning fork with A’ = 435 Hz. In 1885 at an international conference in Vienna this frequency was adopted as the international standard pitch for the tone A’; the frequency was called the standard musical pitch. Since Jan. 1, 1936, an all-Union standard pitch of A’ = 440 Hz has been in effect in the USSR.


MuzykaVnaia akustika. Edited by N. A. Garbuzov. Moscow-Leningrad, 1940.
The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.

tuning fork

[′tün·iŋ ‚fȯrk]
A U-shaped bar for hard steel, fused quartz, or other elastic material that vibrates at a definite natural frequency when struck or when set in motion by electromagnetic means; used as a frequency standard.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.

tuning fork

a two-pronged metal fork that when struck produces a pure note of constant specified pitch. It is used to tune musical instruments and in acoustics
Collins Discovery Encyclopedia, 1st edition © HarperCollins Publishers 2005
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Each child also underwent a tuning-fork test, examination under microscopy, repeat tympanometry, stapedial reflex test, and pure-tone audiometry.
"The Reliquaries of Trees": The reliquaries of trees / are sapling bone chainlink suspended, / lawn stump rooting pipe dry, / avenues tuning-forked to power lines, / patchwork arcanum of mountainside / (when seen from above) / and the sawdust cenotaphs of lumberyards--// where the woods mob in unruly, / try to see past the wind's shoulders / to where the kill site was, / crowd at the edge of roads laid to tell them / there's nothing to see here, nothing to see, / rub rooftops for a blessing pray, / and queue for the time of their own haunting.