Cymbals - Sound production
The cymbal is both vibration generator and resonator.
Sound is produced by striking one cymbal against the other. This causes mainly the rim to vibrate while the center remains motionless. It is these vibrations that produce sound and for this reason the rims of the plates are also struck against each other while they are held by the straps in the center. The cymbal's inherent elasticity and long decay allow the vibrations to develop and produce the reverberation (sustain), the duration of which depends greatly on the alloy, the thickness and the size of the plate.
To avoid creating an air pocket between the plates they must overlap when they are brought together. Should an air pocket arise, the sound is dull and flat.
After the crash – the plates should touch each other only very briefly – the cymbals are immediately held apart, and in most cases the sound is allowed to die away naturally. In some traditions and schools the different parts of the plate are not crashed against each other simultaneously; first the top part is crashed, then the lower (the part furthest away from the musician). The sound is almost that of a grace note.
Because a struck cymbal produces a large number of inharmonic partials a metallic sound results which is also harsh if the oscillation frequency is high. The pitch cannot easily be determined and has the character of noise.
The pitch is determined by the alloy and the weight of the plates, each plate having a slightly different pitch in order to produce a sound rich in overtones. Heavier plates of the same diameter sound deeper. As a general rule, the bigger the cymbal, the lower the pitch.