Tritone

For other uses, see Tritone (disambiguation).
"Devil's Chord" redirects here. For the Doctor Who episode, see The Devil's Chord.
tritone
Inversetritone
Name
Other namesaugmented fourth, diminished fifth, the Devil’s interval (obscure)
AbbreviationTT, A4, d5
Size
Semitones6
Interval class6
Just intervalPythagorean: 729:512, 1024:729
5-limit: 25:18, 36:25; 45:32, 64:45
7-limit: 7:5, 10:7
13-limit: 13:9, 18:13
Cents
12-Tone equal temperament600
Just intonationPythagorean: 612, 588
5-limit: 569, 631; 590, 610
7-limit: 583, 617
13-limit: 563, 637

In music theory, the tritone is defined as a musical interval spanning three adjacent whole tones (six semitones).[1] For instance, the interval from F up to the B above it (in short, F–B) is a tritone as it can be decomposed into the three adjacent whole tones F–G, G–A, and A–B.

Narrowly defined, each of these whole tones must be a step in the scale, so by this definition, within a diatonic scale there is only one tritone for each octave. For instance, the above-mentioned interval F–B is the only tritone formed from the notes of the C major scale. More broadly, a tritone is also commonly defined as any interval with a width of three whole tones (spanning six semitones in the chromatic scale), regardless of scale degrees. According to this definition, a diatonic scale contains two tritones for each octave. For instance, the above-mentioned C major scale contains the tritones F–B (from F to the B above it, also called augmented fourth) and B–F (from B to the F above it, also called diminished fifth, semidiapente, or semitritonus);[2] the latter is decomposed as a semitone B–C, a whole tone C–D, a whole tone D–E, and a semitone E–F, for a total width of three whole tones, but composed as four steps in the scale. In twelve-equal temperament, the tritone divides the octave exactly in half as 6 of 12 semitones or 600 of 1,200 cents.[3]

In classical music, the tritone is a harmonic and melodic dissonance and is important in the study of musical harmony. The tritone can be used to avoid traditional tonality: "Any tendency for a tonality to emerge may be avoided by introducing a note three whole tones distant from the key note of that tonality."[4] The tritone found in the dominant seventh chord can also drive the piece of music towards resolution with its tonic. These various uses exhibit the flexibility, ubiquity, and distinctness of the tritone in music.

The condition of having tritones is called tritonia; that of having no tritones is atritonia. A musical scale or chord containing tritones is called tritonic; one without tritones is atritonic.

  1. ^ Drabkin, William (20 January 2001). "Tritone". Oxford Music Online. doi:10.1093/gmo/9781561592630.article.28403. ISBN 978-1-56159-263-0. Retrieved August 31, 2020.
  2. ^ E.g., Jacobus Leodiensis, Speculum musicae, Liber secundus, in Jacobi Leodiensis Speculum musicae, edited by Roger Bragard, Corpus Scriptorum de Musica 3/2 ([Rome]: American Institute of Musicology, 1961): 128–31, citations on 192–96, 200, and 229; Jacobus Leodiensis, Speculum musicae, Liber sextus, in Jacobi Leodiensis Speculum musicae, edited by Roger Bragard, Corpus Scriptorum de Musica 3/6 ([Rome]: American Institute of Musicology, 1973): 1–161, citations on 52 and 68; Johannes Torkesey, Declaratio et expositio, London: British Library, Lansdowne MS 763, ff.89v-94v, citations on f.92r,2–3; Prosdocimus de Beldemandis, Tractatus musice speculative, in D. Raffaello Baralli and Luigi Torri, "Il Trattato di Prosdocimo de' Beldomandi contro il Lucidario di Marchetto da Padova per la prima volta trascritto e illustrato", Rivista Musicale Italiana 20 (1913): 731–62, citations on 732–34.
  3. ^ Randel (2003), p. 911. "A prominent element in the whole-tone scale...its symmetry with respect to the octave gives it a special role in twelve-tone music as well."
  4. ^ Smith Brindle, Reginald (1966). Serial Composition. Oxford University Press. p. 66. ISBN 0-19-311906-4.