harmonics

In music, a series (the ‘harmonic series’) of partial vibrations that combine to form a musical tone. When a stretched string or a column of air in a tube is made to vibrate, it does so as a whole, in two halves, three thirds, four quarters, etc., all at the same time. The easiest vibration to hear is that of the whole. It is the lowest note and is called the fundamental. The vibrations of the halves, thirds, quarters, etc., produce a series of fainter, higher pitches at the same time. These are known as the harmonics, or upper partials, or overtones. Instruments vary in their tone colour (or timbre) because of the different number and different intensity of the harmonics. An oboe has many harmonics, while a flute has few.