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Tritone

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tritone
Inversetritone
Name
Other namesaugmented fourth, diminished fifth
AbbreviationTT
Size
Semitones6
Interval class6
Just interval7:5, 10:7, 45:32...
Cents
Equal temperament600
Just intonation583, 617, 590...
The augmented fourth between C and F# forms a tritone.
The augmented fourth between C and F# forms a tritone.

The tritone (tri- or three and tone) is a musical interval that spans three whole tones. The tritone is the same as an augmented fourth, which in equal temperament is enharmonic to a diminished fifth.

Contents

[edit] Definition and Nomenclature

Only the augmented fourth consists of three whole tones in meantone temperament. This is where the term is derived. Calling the diminished fifth a "tritone" is parlance. Writers often use the term tritone to mean specifically half of an octave from a given tone, without regard to what system of tuning it may belong to. Two tritones add up to six whole tones, which in meantone temperament is a diesis less than an octave, but equal to a perfect octave in equal temperament, where the diesis is tempered out. A common symbol for tritone is TT. It is also sometimes called a tritonus, the name used in German. An equal-tempered tritone may be heard here.

[edit] Historical Uses

The tritone is a restless interval, classed as a dissonance in Western music from the early Middle Ages through the end of the common practice period. The name diabolus in musica ("the Devil in music") has been applied to the interval from at least the early eighteenth century. Telemann in 1733 notes that "Hier ist mit fleiss ein mi contra fa angebracht, welches die alten den satan in der music nenneten," while Mattheson in 1739 writes that the "alten Solmisatores dieses angenehme Intervall mi contra fa oder den Teufel in der Music genannt haben."<ref>Reinhold Hammerstein, Diabolus in Musica: Studien zur Ikonographie der Musik im Mittelalter, Bern: Francke Verlag, 1974. p. 7.</ref> Although both of these authors cite the association with the devil as from the past, there are no known citations of this term from the Middle Ages, as is commonly asserted. (Suggestions that singers were excommunicated or otherwise punished by the church for invoking this interval are likewise fanciful). However, avoidance of the interval for musical reasons has a long history, stretching back to the parallel organum of the Musica Enchiriadis.

In Baroque and Classical music, the tritone is one of the defining intervals of the dominant-seventh chord and two tritones separated by a minor third give the fully-diminished seventh chord its characteristic sound. In minor, the diminished triad (comprising two minor thirds which together add up to a tritone) appears on the second scale degree, and thus features prominently in the progression iio-V-i. Often, the inversion iio6 is used to move the tritone to the inner voices as this allows for stepwise motion in the bass to the dominant root. In three-part counterpoint, free use of the diminished triad in first inversion is permitted, as this eliminates the tritone relation to the bass.<ref>Jeppesen, Knud: "The Polyphonic Style of the Sixteenth Century", Dover, 1992, ISBN: 0-486-27036-X (pbk)</ref>

The tritone was exploited heavily in the Romantic period as an interval of modulation for its ability to evoke a strong reaction by moving quickly to distantly related keys. Later on, in twelve-tone music, serialism, and other 20th century compositional idioms it came to be considered as a neutral interval.<ref>Persichetti, V., "Twentieth-Century Harmony: Creative Aspects and Practice", W. W. Norton & Company, 1961, ISBN: 0393095398</ref>

The equal-tempered tritone (a ratio of <math>\sqrt{2}:1</math> or 600 cents) is unique in being its own octave inversion. Note that in other meantone tunings, the augmented fourth and the diminished fifth are distinct intervals because neither is exactly half an octave. In any meantone tuning near to 2/9 comma meantone the augmented fourth will be near to the ratio 7/5 and the diminished fifth to 10/7, which is what these intervals are taken to be in septimal meantone temperament. In 31 equal temperament, for example, the diminished fourth, or tritone proper, is 580.6 cents, whereas a 7/5 is 582.5 cents.

[edit] Occurrence

The tritone occurs naturally between the 4th and 7th scale degrees of the major scale (for example, in C major F to B), and depending on which of the two notes occurs in the bass, it is either an augmented 4th, or a diminished 5th. Its most common occurrence is between these scale degrees, in either inversion, when played as the third and seventh of the dominant seventh chord. The sound of the tritone in this chord is arguably what gives it its strong tendency towards resolution.

  • The tritone interval is used in the musical Deutsch tritone paradox.
  • In jazz harmony, the tritone is both part of the dominant chord and its substitute dominant (also known as the sub V chord). Because they share the same tritone, they are possible substitutes for one another. This is known as tritone substitution.

For example, in the key of C Major, the primary dominant G7 may be substituted with D♭7 which is its substitute dominant. Note that both have the same tritone (B and F, or enharmonically C♭ and F in reference to the D♭7 chord). In classical music Liszt uses the tritone in the same way in "Au bord d´une source" (B as dominant for B-flat) and many other places.
This device can also be used in jazz improvisation, whereupon an improviser may use the chord tones of the D♭7 on a G7 chord to create an altered chord characteristic of jazz improvisation.
The D♭7 chord tones spell out the ♭5, ♭7, ♭9 and maj3rd of the G7 chord, thus effectively outlining both the guide tones (maj3rd and ♭7) of the G7 as well as two altered notes (♭5 and ♭9).

[edit] Musical examples

Diatonic intervalsedit
Perfect : unison (0) | fourth (5) | fifth (7) | octave (12)
Major : second (2) | third (4) | sixth (9) | seventh (11)
Minor : second (1) | third (3)| sixth (8) | seventh (10)
Augmented : unison (1) | second (3) | third (5) | fourth (6) | fifth (8) | sixth (10) | seventh (12)
Diminished : second (0) | third (2) | fourth (4) | fifth (6) | sixth (7) | seventh (9) | octave (11)
semitones of equal temperament are given in brackets
  • An episode of Charmed entitled "We All Scream for Ice Cream" has an ice cream truck playing a tritone to atract demons so that the ice cream man can kill them

[edit] References

<references/>

[edit] External links

[edit] See also

da:Tritonus de:Tritonus et:Tritoon es:Tritono fr:Triton (musique) it:Tritono he:טריטון (מוזיקה) lt:Tritonis nl:Tritonus ja:三全音 pl:Tryton (muzyka) ru:Тритон (интервал) fi:Tritonus sv:Överstigande kvart

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