The harmonic series (also called an overtone series), which operates behind all musical tone production, is an important basic concept in organ registration.
The terms “harmonic series” or “overtone series” refer to several pitches (harmonics, overtones, or partials) that are produced when a musical instrument is sounded (such as a string, bar, or air column). We refer to each element of the series as a harmonic, overtone, or partial. An entire series of harmonics is sounded whenever the musical instrument plays a single tone. This means that the perceived tone is actually composed of many pitches (harmonics, overtones, or partials).
Click on the example to hear the partials played from a harmonic series. The first note heard is the first partial, proceding through the eighth (including the seventh partial that is shown as a dot in the illustration).