Harmonics

Harmonics, pronounced hahr MAHN ihks, are the components of a musical tone. A tone is actually a blend of several separate tones. This blend, called a composite tone, is caused by a set of vibrations, such as those made by a musical instrument or the human voice. For example, a violin string vibrates over its entire length. But it also vibrates in segments, called partials, which are shorter than the total length of the string. The string vibrates in segments such as one-half, one-third, or one-fourth, of the string. Each vibrating segment produces a separate tone, called an overtone.

The first harmonic, called a fundamental, is the lowest tone. It results from the vibration of the whole violin string. Other harmonics, called overtones, come from the various vibrating segments. The second harmonic, also called the first overtone, vibrates in two segments at a frequency twice that of the fundamental, and is an octave higher. Other overtones have vibration frequencies three or more times that of the fundamental. In most cases, the higher overtones are produced with less intensity (loudness) than the lower ones. The fundamental and overtones combine to produce one complete tone that is the same pitch as the fundamental.

The number and intensity of a tone's harmonics determine the timbre (quality) of the tone. The timbre is largely responsible for the different sounds produced by various musical instruments, even when they play the same note. In the human voice, harmonics create vowel sounds and the different tone qualities that separate the sound of one voice from another. Sounds with strong high harmonics are often called resonant or rich in quality, and sounds with relatively low weak harmonics are called soft or muted.

Contributor: Thomas W. Tunks, Ph.D., Associate Dean, Meadows School of the Arts, Southern Methodist Univ.

Harmonics

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