String harmonic

Playing astring harmonic(aflageolet) is astring instrumenttechniquethat uses thenodesof naturalharmonicsof a musicalstringto isolateovertones.Playing string harmonics produces high pitched tones, often compared in timbre to a whistle or flute.Overtones can be isolated "by lightly touching the string with the finger instead of pressing it down" against thefingerboard(withoutstopping).For some instruments this is a fundamental technique, such as the Chineseguqin,where it is known asfan yin(Âm bội,lit. "floating sound" ), and the Vietnameseđàn bầu.

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.

Overtones

Main article:Harmonic

When astringis plucked or bowed normally, the ear hears thefundamental frequencymost prominently, but the overall sound is also colored by the presence of variousovertones(frequencies greater than 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 (seetimbre).A harmonic overtone has evenly spaced nodes along the string, where the string does not move from its resting position.

Nodes

Table of harmonics, indicating in colors on which positions the same overtones occur

The nodes of natural harmonics are located at the following points along the string:

Harmonic	Stop note	Sounded note relative to open string	Centsabove open string	Cents reduced to one octave	Length fraction	Audio
2	octave	octave(P8)	1,200.0	0.0	1⁄2
3	just perfect fifth	P8 + justperfect fifth(P5)	1,902.0	702.0	1⁄3,2⁄3
4	justperfect fourth	2P8	2,400.0	0.0	1⁄4,3⁄4
5	just major third	2P8 +just major third(M3)	2,786.3	386.3	1⁄5to4⁄5
6	justminor third	2P8 + P5	3,102.0	702.0	1⁄6,5⁄6
7	septimal minor third	2P8 +septimal minor seventh(m7)	3,368.8	968.8	1⁄7to6⁄7
8	septimal major second	3P8	3,600.0	0.0	1⁄8,3⁄8,5⁄8,7⁄8
9	Pythagorean major second	3P8 +Pythagorean major second(M2)	3,803.9	203.9	1⁄9,2⁄9,4⁄9,5⁄9,7⁄9,8⁄9
10	just minorwhole tone	3P8 + just M3	3,986.3	386.3	1⁄10,3⁄10,7⁄10,9⁄10
11	greater undecimalneutral second	3P8 + lesser undecimaltritone	4,151.3	551.3	1⁄11to10⁄11
12	lesser undecimal neutral second	3P8 + P5	4,302.0	702.0	1⁄12,5⁄12,7⁄12,11⁄12
13	tridecimal 2/3-tone	3P8 + tridecimalneutral sixth(n6)	4,440.5	840.5	1⁄13to12⁄13
14	2/3-tone	3P8 + P5 +septimal minor third(m3)	4,568.8	968.8	1⁄14,3⁄14,5⁄14,9⁄14,11⁄14,13⁄14
15	septimal (or major)diatonic semitone	3P8 + justmajor seventh(M7)	4,688.3	1,088.3	1⁄15,2⁄15,4⁄15,7⁄15,8⁄15,11⁄15,13⁄15,14⁄15
16	just (or minor) diatonic semitone	4P8	4,800.0	0.0	1⁄16,3⁄16,5⁄16,7⁄16,9⁄16,11⁄16,13⁄16,15⁄16

Above, the length fraction is the point, with respect to the length of the whole string, the string is lightly touched. It is expressed as a fraction⁠n/m⁠,wheremis the mode (2 through 16 are given above), andnthe node number. The node number for a given mode can be any integer from 1 tom− 1.However, certain nodes of higher harmonics are coincident with nodes of lower harmonics, and the lower sounds overpower the higher ones. For example, mode number 4 can be fingered at nodes 1 and 3; it will occur at node 2 but will not be heard over the stronger first harmonic. Ineffective nodes to finger are not listed above.

The fret number, which shows the position of the node in terms of half tones (or frets on a fretted instrument) then is given by:

$F=\log _{s}{\frac {m}{m-n}}$

Withsequal to thetwelfth root of two,notatedsbecause it's the first letter of the word "semitone".

Artificial harmonics

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.

Natural versus artificial harmonic

When a string is only lightly pressed by one finger (that is, isolating overtones of the open string), the resulting harmonics are callednatural harmonics.However, when a string is held down on the neck in addition to being lightly pressed on a node, the resulting harmonics are calledartificial harmonics.In this case, as the total length of the string is shortened, the fundamental frequency is raised, and the positions of the nodes shift accordingly (that is, by the same number of frets), thereby raising the frequency of the overtone by the same interval as the fundamental frequency.

Artificial harmonics are produced by stopping the string with the first or second finger, and thus making an artificial 'nut,' and then slightly pressing the node with the fourth finger. By this means harmonics in perfect intonation can be produced in all scales.

— Grove's Dictionary of Music and Musicians(1879)

Artificial harmonics are more difficult to play than natural harmonics, but they are not limited to the overtone series of the open strings, meaning they have much greater flexibility to play chromatic passages. Unlike natural harmonics, they can be played withvibrato.

This technique, like natural harmonics, works by canceling out the fundamental tone and one or more partial tones by deadening their modes of vibration. It is traditionally notated using two or three simultaneousnoteheadsin onestaff:a normal notehead for the position of the firmly held finger, a square notehead for the position of the lightly pressed finger, and sometimes, a small notehead for the resulting pitch.

The most commonly used artificial harmonic, due to its relatively easy and naturalfingering,is that in which, "the fourth finger lightly touches the nodal point a perfect fourth above the first finger. (Resulting harmonic sound: two octaves above the first finger or new fundamental.),"followed by the artificial harmonic produced when, "the fourth finger lightly touches the nodal point a perfect fifth above the first finger (Resulting harmonic sound: a twelfth above the first finger or new fundamental.),"and, "the third finger lightly touches the nodal point a major third above the first finger. (Resulting harmonic sound: two octaves and a major third above the first finger or new fundamental.)"

In some cases, especially in the electric guitar technique, it is common to refer to Pinch Harmonics as Artificial Harmonics (AH) and to refer to harmonics produced by other means as Natural Harmonics.

Guitar

The fundamental and the double- and triple-frequency overtones of a guitar string.

There are a few harmonic techniques unique to guitar.

Pinch harmonics

Pinch harmonics performed on an acoustic guitar

A pinch harmonic (also known as squelch picking, pick harmonic or squealy) is a guitar technique to achieve artificial harmonics in which the player's thumb or index finger on the picking hand slightly catches the string after it is picked,canceling (silencing) the fundamental frequency of the string, and letting one of theovertonesdominate. This results in a high-pitched sound which is particularly discernible on an electrically amplified guitar as a "squeal".

Tapped harmonics

Tapped harmonics were popularized byEddie Van Halen.This technique is an extension of thetappingtechnique. 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 tapping finger bounces lightly on and off the fret. The open string technique can be extended to artificial harmonics. For instance, for anoctaveharmonic (12-fret nodal point) press at the third fret, and tap the fifteenth fret, as12 + 3 = 15.

String harmonics driven by a magnetic field

This technique is used by effect devices producing a magnetic field that can agitate fundamentals and harmonics of steel strings. There are harmonic mode switches as provided by newer versions of theEBowand by guitars built in sustainers like theFernandes Sustainerand the Moog Guitar. Harmonics control by harmonic mode switching and by the playing technique is applied by theGuitar Resonatorwhere harmonics can be alternated by changing the string driver position at the fretboard while playing.

See also

• 3rd bridge