String Properties

The vibration of the strings on stringed instruments have the form of standing waves which produce a fundamental frequency and all harmonics of that fundamental frequency simultaneously. These frequencies depend upon the tension, mass and length of the string. The harmonics make the sound timbre fuller and richer than the fundamental alone. The particular mix of harmonics present depends upon the method of excitation of the string.

String Excitation

The frequencies produced by stretched strings are determined by the tension, mass and length of the strings, and consist of a fundamental frequency and all harmonics of that fundamental. Even though these frequencies are determined, the timbre of the sound produced by the string can vary considerably depending upon the method of excitation of the string. In the violin family the string may be bowed or plucked (pizzicato). In the piano the string is struck by a felt hammer, and in the harpsichord the strings are plucked by a "quill".

Even when the form of excitation is established, there are differences in harmonic content depending upon the location of excitation on the string. If a violin is bowed close to the bridge (sul ponticello) then the sound is brighter with more harmonic content. If bowed further from the bridge (sul tasto) then the sound is darker, more mellow with less harmonic content.

String Instrument Resonances

In addition to the string properties and the method of excitation of strings, the sound timbre is significantly affected by resonances in the body of the instrument itself. In the case of the violin , the resonances have been thoroughly studied and to them are attributed the excellent qualities of the legendary Stradivarius and others. In general, the violin family instruments exhibit an air resonance and a main wood resonance.