Tuning fork

It resonates at a specific constant pitch when set vibrating by striking it against a surface or with an object, and emits a pure musical tone once the high overtones fade out.

The tuning fork was invented in 1711 by British musician John Shore, sergeant trumpeter and lutenist to the royal court.

The main reason for using the fork shape is that, unlike many other types of resonators, it produces a very pure tone, with most of the vibrational energy at the fundamental frequency.

When the tuning fork is struck, little of the energy goes into the overtone modes; they also die out correspondingly faster, leaving a pure sine wave at the fundamental frequency.

However, there is still a tiny motion induced in the handle in its longitudinal direction (thus at right angles to the oscillation of the prongs) which can be made audible using any sort of sound board.

[4] Bone conduction using a tuning fork is specifically used in the Weber and Rinne tests for hearing in order to bypass the middle ear.

Thus when a solid sheet is slid in between the prongs of a vibrating fork, the apparent volume actually increases, as this cancellation is reduced, just as a loudspeaker requires a baffle in order to radiate efficiently.

The most popular of these is the Rhodes piano, in which hammers hit metal tines that vibrate in the magnetic field of a pickup, creating a signal that drives electric amplification.

The Accutron, an electromechanical watch developed by Max Hetzel[9] and manufactured by Bulova beginning in 1960, used a 360-hertz steel tuning fork as its timekeeper, powered by electromagnets attached to a battery-powered transistor oscillator circuit.

[12] Orthopedic surgeons have explored using a tuning fork (lowest frequency C=128) to assess injuries where bone fracture is suspected.

[citation needed] Established practice, however, requires an X-ray regardless, because it's better than missing a real fracture while wondering if a response means a sprain.

[14] A radar gun that measures the speed of cars or a ball in sports is usually calibrated with a tuning fork.

Doubled and H-type tuning forks are used for tactical-grade Vibrating Structure Gyroscopes and various types of microelectromechanical systems.