Triad (music)

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In music or music theory, a triad is a tonal or diatonic tertian trichord. In other words, a chord with three distinct tones, built from thirds (3rd intervals), and having a diatonic function. The three tones of a triad constructed in stock root-position are called, from lowest pitched tone (up) to highest:

• the Root
• the Third (whose interval is a major third or minor third above the root)
• and the Fifth (whose interval is a major or minor third above the third, and a diminished, perfect, or augmented fifth above the root).

The function of a given triad is determined primarily by its root tone and the degree of the scale it corresponds to, but also by the quality of the chord (the exact third and fifth).

There are four basic triads: Major, minor, diminished and augmented. All but the augmented triad are natural to and can be construtcted from the Major (or diatonic) scale. Triads (and all other larger tertian chords) are built by combining or stacking every other tone the scale above each individual degree (or scale-tone) of the given seven-tone scale. The four triads are built of the following intervals:

• Major triads contain a major third and perfect fifth interval, symbolized: R 3 5 (or 0-4-7 as semitones)
• minor triads contain a minor third, and perfect fifth, symbolized: R ♭3 5 (or 0-3-7)
• diminished triads contain a minor third, and diminished fifth, symbolized: R ♭3 ♭5 (or 0-3-6)
• augmented triads contain a major third, and augmented fifth, symbolized: R 3 ♯5 (or 0-4-8)

Primary triads of a diatonic key (Major or minor) include the tonic, subdominant, and dominant degree chords, otherwise symbolized: I, IV, and V respectively.

See also: Tertian harmony

[edit] External links

• Tonalsoft Encyclopaedia of Tuning

Chords
By Type	Triads	Major · Minor · Augmented · Diminished
	Sevenths	Major · Minor · Dominant · Diminished · Half-diminished · Minor-Major · Augmented major · Augmented minor
	Extended	Ninth · Eleventh · Thirteenth
	Other	Sixth · Augmented sixth · Altered · Added tone · Polychord · Quartal and quintal · Tone cluster
By Function	Diatonic	Tonic · Dominant · Subdominant · Submediant
	Altered	Borrowed · Neapolitan chord · Secondary dominant · Secondary subdominant