Chord Theory

Chord Theory 4: Sus Chords

Unlike all of the chords we have learned about so far, suspended chords are not major nor minor, and are not built in thirds.

Suspended Chords

The only difference between a major and minor triad is the type of third in the chord. The presence of a major third indicates that the triad is major, while a minor third indicates a minor triad. For instance a Cmaj triad has an E natural whereas a Cmin triad has an Eb.

In short, the third is what we use to identify the quality of the chord – i.e. whether it is major or minor (of course the fifth will determine whether a chord is augmented or diminished but that is a topic for another post). In contrast, suspended chords do not contain a third. This means that suspended chords cannot be major or minor, and therefore do not have a ‘quality’ in the traditional sense – although they do have their own unique and appealing sound.

Like major and minor triads, suspended chords do still have a root (obviously) and a perfect fifth, but the third is replaced with another note. In suspended fourth chords the third is replaced with the perfect fourth (the note F in the key of C), and in suspended second chords, the third is replaced with the major second (the note ‘D’ in the key of C). This gives us the formulae 1, 4, 5 for suspended fourth chords, and 1, 2, 5 for suspended second chords.

In classical harmony, a ‘suspended’ note is a note which replaces a chord note. Therefore, suspended chords are best thought of as ordinary major or minor chords but where the third has been ‘suspended’ (i.e. replaced) with the second or fourth of the scale.

Sus4 Chords

Suspended fourth chords have the third replaced with a perfect fourth. Suspended fourth chords are usually abbreviated to ‘sus4’ or occasionally just ‘sus’.

A sus4 chord should be thought of as a either: (1) a major triad with the third raised by a semitone, or; (2) a minor triad with the third raised by a tone.

Sus2 Chords

Suspended second chords have the third replaced with a major second. On sheet music, the abbreviation for suspended second is always ‘sus2’ (never just ‘sus’).

A sus2 chord should be thought of as a either: (1) a major triad with the third lowered by a tone, or; (2) a minor triad with the third lowered by a semitone.

Suspended Seventh Chords

Adding a minor seventh above a suspended fourth chord creates a suspended seventh chord. Major sevenths are almost never added to sus4 chords because they create a tritone with the fourth in the chord (such a chord would therefore be better thought of as a dominant-type chord, built from a different root – a more detailed explanation of dominant chords, and the importance of the tritone will be covered in a future post).

It is also uncommon to add a seventh to a sus2 chord. Sus2 chords do not have the harmonic momentum found in sus4 chords – adding an extra note on top would only further weaken the suspended effect and harmonic momentum. Therefore, the only real-world suspended seventh chord, uses a minor seventh on top of a sus4 chord. The formula for a 7sus4, or simply 7sus, chord is therefore 1, 4, 5, b7.

Of course, we can build 9sus4 (1, 4, 5, b7, 9) and 13sus4 (1, 4, 5, b7, 9, 13) chords as well – though its impossible to have an ’11sus4′ because the eleventh and the fourth are the same note. It is also common to flatten the ninth of a suspended seventh chord, to increase its harmonic momentum, as is the case in 7sus4b9 (1, 4, 5, b7, b9) and 13sus4b9 (1, 4, 5, b7, b9, 13) chords.

Table of Suspended Chord Formulas

The following table summarises everything covered so far in this post.

Chord Name Formula Actual Notes on C
sus2 1 2 5 C D G
sus4 1 4 5 C F G
sus4 1 4 5 C F G
7sus4 1 4 5 b7 C F G Bb
9sus4 1 4 5 b7 9 C F G Bb D
13sus4 1 4 5 b7 9 13 C F G Bb D A
7sus4b9 1 4 5 b7 b9 C F G Bb Db
13sus4b9 1 4 5 b7 b9 13 C F G Bb Db A

2 replies on “Chord Theory 4: Sus Chords”

Hey awesome summary of sus chords. I didn’t know that 7th’s typically aren’t added to sus2 chords, so that was interesting to learn.

I think there’s a typo in the table at the end of the article. The actual notes in the 13sus4b9 should be C F G bB bD A.

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