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a constituent tone of a complex vibration (mechanical, including sound and electrical, vibrations) having a frequency higher than that of the fundamental tone. The ratio of the frequencies of the overtones to the fundamental tone is shown by breaking the complex vibration down into a series. Overtones whose frequencies are integral multiples of the frequency of the fundamental are called harmonic overtones, or harmonics. All other overtones are nonharmonic. An overtone can be separated by means of a resonator.
A musical sound is composed of the fundamental tone and the harmonic overtones, or partials. Overtones occur because a sounding body (string, air column) vibrates not only as a whole but also in sections (1/2, 1/3, 1/4). Overtones are weaker than the fundamental tone, and thus blend with it. As a result, they are not detected by the ear. However, the presence and relative force of each overtone determine the timbre of a sound. Nonharmonic overtones are inherent to sirens, bells, and various noises.