String harmonic

Playing string harmonics produces high pitched tones, often compared in timbre to a whistle or flute.

[1][2] Overtones can be isolated "by lightly touching the string with the finger instead of pressing it down" against the fingerboard (without stopping).

[2] For some instruments this is a fundamental technique, such as the Chinese guqin, where it is known as fan yin (泛音, lit.

(Resulting harmonic sound: two octaves and a major third above the first finger or new fundamental.

This results in a high-pitched sound which is particularly discernible on an electrically amplified guitar as a "squeal".

The note is fretted as usual, but instead of striking the string the excitation energy required to sound the note is achieved by tapping at a harmonic nodal point.

The open string technique can be extended to artificial harmonics.

This technique is used by effect devices producing a magnetic field that can agitate fundamentals and harmonics of steel strings.

Playing a harmonic on a string. Here, "+7" indicates that the string is held down at the position for raising the pitch by 7 semitones.
Table of harmonics, indicating in colors on which positions the same overtones occur
Artificial harmonics on a G fundamental, as written (below) and as sounding (top). The round note (below) is pressed with one finger, and the square note is lightly touched with another one. Play
Natural versus artificial harmonic
The fundamental and the double- and triple-frequency overtones of a guitar string.
Pinch harmonics performed on an acoustic guitar