The Harmonic Series
As an instrument (a string, for example) vibrates, we perceive a single pitch. That pitch, the “fundamental,” is produced as the entire string vibrates as a single unit (see “fundamental” to the right).
While the string vibrates as a single unit, it also vibrates in halves, in thirds, fourths, etc. Each of these other ways of vibrating also produces a pitch, called an overtone.
Although we do not usually perceive these fainter pitches (or overtones) as distinctly as the fundamental, they contribute to the tone quality. Stopped flute pipes, for example, have relatively weak upper partials, while string pipes have strong upper partials.
