Component intervals fromroot | |
---|---|
diminished fifth (tritone) | |
minor third | |
root | |
Tuning | |
45:54:64;[1] 54:45=6:5 &64:45[2] | |
Forte no. / | |
3-10 / |
Inmusic theory, adiminished triad is atriad consisting of twominor thirds above theroot.[3] It is aminor triad with a lowered (flattened)fifth. When usingchord symbols, it may be indicated by the symbols "dim", "o", "m♭5", or "MI(♭5)".[4] However, in most popular-music chord books, the symbol "dim" or "o" represents adiminished seventh chord (a four-tone chord), which in some modern jazz books and music theory books is represented by the "dim7" or "o7" symbols.
For example, the diminished triad built on B, written as Bo, has pitches B-D-F:
The chord can be represented by theinteger notation {0, 3, 6}.
In thecommon practice period, the diminished triad is considereddissonant because of thediminished fifth (or tritone).
Inmajor scales, a diminished triad occurs only on the seventhscale degree. For instance, in the key of C, this is a B diminished triad (B, D, F). Since the triad is built on the seventh scale degree, it is also called theleading-tone triad. This chord has adominant function. Unlike thedominant triad ordominant seventh, the leading-tone triad functions as aprolongational chord rather than a structural chord since the strong root motion by fifth is absent.[6]
On the other hand, innatural minor scales, the diminished triad occurs on the second scale degree; in the key of C minor, this is the D diminished triad (D, F, A♭). This triad is consequently called thesupertonic diminished triad. Like the supertonic minor triad found in a major key, the supertonic diminished triad has apredominant function, almost always resolving to a dominant functioning chord.[7]
If the music is in a minor key, diminished triads can also be found on the raised seventh note,♯viio. This is because theascending melodic minor scale has a raised sixth and seventh degree. For example, the chord progression♯viio–i is common.
The leading-tone diminished triad and supertonic diminished triad are usually found infirst inversion (viio6 and iio6, respectively) since the spelling of the chord forms a diminished fifth with the bass.[6] This differs from thefully diminished seventh chord, which commonly occurs inroot position.[8] In both cases, the bass resolves up and the upper voices move downwards incontrary motion.[8]
Walter Everett writes that "Inrock andpop music, the diminished triad nearly always appears on the second scale degree, forming a generally maudlin and dejected iio with its members, 2–4–♭6."[9] Songs that feature iio includeSanto & Johnny's "Sleep Walk",Jay and the Americans' "Cara Mia", andthe Hollies' "The Air That I Breathe".[9] Not so rare but rare enough so as to imply knowledge of and conscious avoidance on the part of rock musicians, examples of its use includeOasis' "Don't Look Back in Anger",David Bowie's "Space Oddity", and two inDaryl Hall's "Everytime You Go Away".[10]
The viio in major keys is relatively less common than the iio, but still does happen. It is almost always used totonicize the relative minor, in progressions such as viio–V7/vi–vi, which resembles iio–V7–i in the relative minor.
In atwelve-tone equal temperament, a diminished triad has threesemitones between the third and fifth, three semitones between the root and third, and six semitones between the root and fifth.
In5-limitjust intonation, the diminished chord on VII (in C: B–D–F) is 15:8, 9:8, and 4:3, while on II (in C: D–F–A♭) it is 9:8, 4:3, and 8:5 (135:160:192). According toGeorg Andreas Sorge, thetrumpet, in its overtone series on C, gives the diminished triad E–G–B♭ = 5:6:7 ("perfect diminished chord"[11]), but the7 is too flat and 45:54:64 is preferred.[1]Helmholtz describes the diminished triad as1 − D | F, giving a just minor third and Pythagorean minor third (45:54:64) in the notation system used inOn the Sensations of Tone as a Physiological Basis for the Theory of Music.[12]
PlayPerfectⓘ,Preferredⓘ (5-limit major), or5-limit minorⓘ on C.
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