Resonators
From AudioLexic
A resonator is a device or system that exhibits resonance or resonant behavior. Many objects that use resonant effects are referred to simply as resonators. Examples of resonators are discussed in this article. A cavity resonator is a resonator composed of a space that is usually surrounded by a dielectric that uses resonance to select a specific band of frequencies.
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[edit] Cavity resonators
The cavity has interior surfaces which reflect a wave, usually electromagnetic, of a specific frequency. When a wave that is resonant with the cavity enters, it bounces back and forth within the cavity, with low loss (See standing wave). As more wave energy enters the cavity, it combines with and reinforces the standing wave, increasing its intensity.
[edit] Examples
Some common examples of cavity resonators include the tube of a flute, and the body of a violin (this latter also being an example of a Helmholtz resonator). The klystron tube in a microwave oven (see also magnetron).
[edit] Musical instruments
Most musical instruments include resonators to enhance the sound of the instrument. In many keyboard percussion instruments, below the centre of each note is a tube, which is an acoustic cavity resonator, referred to simply as the resonator. The length of the tube varies according to the pitch of the note, with higher notes having shorter resonators. The tube is open at the top end and closed at the bottom end, creating a column of air which resonates when the note is struck. This adds depth and volume to the note. In string instruments, the body of the instrument is a resonator.
In Camille Saint-Saëns' Danse Macabre, a skeleton's dance is depicted by a xylophone. Since the instrument in Saint-Saëns' day did not have resonators, it is often performed with resonators removed (or covered). This makes sound of the instrument more brittle and bone-like. The tremolo effect of a vibraphone is obtained by a mechanism which opens and shuts the resonators. String instruments such as the bluegrass banjo may also have resonators. Many five-string banjos have removable resonators, to allow the instrument to be used with resonator in bluegrass style, or without in folk music style. The term resonator, used by itself, may also refer to the resonator guitar.
[edit] See also
[edit] External links
- "Acoustics of Resonators" by Leigh Howard Stevens
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