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String harmonic

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Playing a harmonic on a string. Here, "+7" indicates that the string is held down at the position for raising the pitch by 7 half notes, that is, at the seventh fret for a fretted instrument.

Playing a string harmonic is a string instrument technique that uses the nodes of natural harmonics of a musical string to produce high pitched tones of varying timbre and loudness. Playing string harmonics produces "high pitched tones, like a whistle's, are produced when the musician lightly touches certain points on a string".[1] "A flute-like sound produced on a string instrument by lightly touching the string with the finger instead of pressing it down"[2] against the fingerboard (without stopping).

Overtones

Main article: Harmonic

When a string is plucked normally, the ear hears the fundamental frequency most prominently, but the overall sound is also colored by the presence of various overtones (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 (see timbre).[3] 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 Cents above open string Cents reduced to one octave Length fraction Audio
2 octave octave (P8) 1,200.0 0.0 1 Playⓘ
3 just perfect fifth P8 + just perfect fifth (P5) 1,902.0 702.0 1⁄2 Playⓘ
4 just perfect fourth 2P8 2,400.0 0.0 1⁄3, 2⁄3 Playⓘ
5 just major third 2P8 + just major third (M3) 2,786.3 386.3 1⁄4, 3⁄4 Playⓘ
6 just minor third 2P8 + P5 3,102.0 702.0 1⁄5 to 4⁄5
7 septimal minor third 2P8 + septimal minor seventh (m7) 3,368.8 968.8 1⁄6, 5⁄6 Playⓘ
8 septimal major second 3P8 3,600.0 0.0 1⁄7 to 6⁄7
9 Pythagorean major second 3P8 + Pythagorean major second (M2) 3,803.9 203.9 1⁄8, 3⁄8, 5⁄8, 7⁄8 Playⓘ
10 just minor whole tone 3P8 + just M3 3,986.3 386.3 1⁄9, 2⁄9, 4⁄9, 5⁄9, 7⁄9, 8⁄9
11 greater undecimal neutral second 3P8 + lesser undecimal tritone 4,151.3 551.3 1⁄10, 3⁄10, 7⁄10, 9⁄10 Playⓘ
12 lesser undecimal neutral second 3P8 + P5 4,302.0 702.0 1⁄11 to 10⁄11
13 tridecimal 2/3-tone 3P8 + tridecimal neutral sixth (n6) 4,440.5 840.5 1⁄12, 5⁄12, 7⁄12, 11⁄12 Playⓘ
14 2/3-tone 3P8 + P5 + septimal minor third (m3) 4,568.8 968.8 1⁄13 to 12⁄13
15 septimal (or major) diatonic semitone 3P8 + just major seventh (M7) 4,688.3 1,088.3 1⁄14, 3⁄14, 5⁄14, 9⁄14, 11⁄14, 13⁄14 Playⓘ
16 just (or minor) diatonic semitone 4P8 4,800.0 0.0 1⁄15, 2⁄15, 4⁄15, 7⁄15, 8⁄15, 11⁄15, 13⁄15, 14⁄15

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 fraction ⁠n/m⁠, where m is the mode (1 through 10 are given above), and n the node number. The node number for a given mode can be any integer from 1 to m − 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:

With s equal to the twelfth root of two, notated s because it's the first letter of the word "semitone".

When a string is held down on the neck, the resulting harmonics are called artificial 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.

Guitar

Tuning a guitar using overtones (listen)
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
Example of pinch harmonic
Pinch harmonic example on the 3rd fret of the G string
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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,[4] canceling (silencing) the fundamental frequency of the string, and letting one of the harmonics dominate. 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 by Eddie van Halen. This technique is an extension of the tapping technique. 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 an octave harmonic (12-fret nodal point) press at the third fret, and tap the fifteenth fret, as 12 + 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 the EBow and by guitar build in sustainers like the Fernandes Sustainer and the Moog Guitar. Harmonics control by harmonic mode switching and by the playing technique is applied by the Guitar Resonator where harmonics can be alternated by changing the string driver position at the fretboard while playing.

See also

References

  1. ^ Kamien, Roger (2008). Music: An Appreciation, p.13. Sixth "brief" edition. McGraw Hill. ISBN 978-0-07-340134-8.
  2. ^ Palisca, Claude V.; ed. (1996). Norton Anthology of Western Music, Volume 1: Ancient to Baroque, glossary, p.601. Third edition. W. W. Norton. ISBN 0-393-96906-1.
  3. ^ "The Physics of Everyday Stuff - The Guitar". www.bsharp.org. Retrieved 2015-08-03.
  4. ^ "Guitar Techniques: Pick Harmonic", XtremeMusician.com. Accessed: December 19, 2017.

Pinch harmonic

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