Guitar harmonics

A guitar harmonic is a musical note played by preventing or amplifying vibration of certain overtones of a guitar string.

Music using harmonics can contain very high pitch notes difficult or impossible to reach by fretting. Guitar harmonics also produce a different sound quality than fretted notes, and are one of many techniques used to create musical variety.

Harmonics are primarily generated manually, using a variety of techniques such as the pinch harmonic. Another method utilizes sound wave feedback from a guitar amplifier at high volume, which allows for indefinite vibration of certain string harmonics. Magnetic string drivers, such as the EBow, also use string harmonics to create sounds that are generally not playable via traditional picking or fretting techniques.

Harmonics are most often played by lightly placing a finger on a string at a nodal point of one of the overtones at the moment when the string is driven. The finger immediately damps all overtones that do not have a node near the location touched. The lowest-pitch overtone dominates the resulting sound.

When a guitar string is plucked normally, the ear tends to hear the fundamental frequency most prominently, but the overall sound is also colored by the presence of various overtones (integer multiples of the fundamental frequency). The fundamental frequency and its overtones are perceived by the listener as a single note; however, different combinations of overtones give rise to noticeably different overall tones (see timbre). A harmonic overtone has evenly spaced nodes along the string, where the string does not move from its resting position.

The nodes of natural harmonics are located at the following points along a guitar's neck. For fretted strings, these locations shift up the fingerboard by the same number of frets, and resulting harmonics are called artificial harmonics.

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