Tuning fork
A tuning fork (deprecated Diapason ) is a metal fork, whose prongs when struck produce a clear, overtones sound. Tuning fork was invented in the 1711 by the military trumpeter John Shore.
- 2.1 In the music
- 2.2 In the medical
- 2.3 Electronic tuning fork watches
- 2.4 vibration probe
Principle
Sound generation
Physically, the tuning fork is a bending vibrator. The tines vibrate when struck in opposite directions. As soon as the prongs move outward, the air is compressed in front of them, while it is diluted between them. When you swing back, the density distribution is reversed. The wave-like propagating pressure differences we perceive as sound.
The sine wave produced may be made visible in different ways, for example with the aid of a stroboscope or a microphone, and an oscilloscope. If one of the prongs attach a needle and this is quickly absorbed after striking a blackened glass plate, the waveform of the oscillation is drawn in the soot.
Reinforcement
Bring to the foot of a chipped tuning fork in contact with a resonating body such as a table top or even the skull bone, the sound produced is amplified and is much clearer to hear.
Suggestion
An often been convicted attempt to resonance in physics is based on two attached to decoupled resonators, on the same frequency calibrated tuning forks: If a fork is activated and stopped a few seconds later, the sound will still sound; the second tuning fork is excited by the light emitted by the first sound wave to vibrate at its resonant frequency.
Use
In the music
At a concert pitch tuning forks tuned to set the mood of musical instruments and used while playing music. In male choruses are occasionally also tuning forks in f ' mood in use.
In Medicine
Tuning forks are also used in medicine in several areas.
In neurology, tuning forks are used for testing the vibration sense, the pallesthesia, used, by treating them in low vibration ( 64 Hz) and touches on points at which a bony prominence is quite superficial, such as the Großzehgrundgelenk or ankles. If there is no perception of vibration, there is a suspicion of neuropathy.
Due to the very simple investigation and inexpensive instrument, it is a good screening method for diabetic polyneuropathy in the context of disease management program in general medical practice. To use the variant comes here Rydel - Seiffer, where you can measure the vibration sense objectively using scaled weights.
In audiology using tuning forks simple preliminary hearing tests can be performed. Best known are sure the Weber test and Rinne test with the help of already rough statements about the location of the fault can be made.
Electronic tuning fork watches
Electronic tuners not necessarily produce sounds, but can always measure the sounds produced by the instrument. In quartz watches quartz watches for a 32,768 Hz is installed, from which can be deduced by simple frequency division by 215 seconds pulses. Since quartz is very hard, the Resonananzfrequenz a crystal block of a few millimeters size is much too high in the megahertz range.
By tuning fork shape can be twice as long quartz rod to accommodate for the same length, and the size is so small that the quartz despite deep resonant frequency fits into a watch case. Also, would straight rods with bending vibrations, which is attached at one end or in the center, leave by their mass shift while swinging quite a lot of vibration energy to their attachment, and therefore oscillate strongly attenuated, while the tuning fork shape the mass transfer through the conflict swing of the two halves the tuning fork is compensated to a large extent.
Before wristwatches have become more precise by counting of quartz vibrations, the company Bulova brought to greater accuracy a clock with visible and audible tuning fork under the name Accutron on the market.
Vibration probe
The vibrating probe is for measuring liquid levels in tanks. It operates according to the principle of the tuning fork.