Audio: suspended chord (0:10)
suspended chord is a brass quartet playing a harmony containing suspended chords in the key of A minor. The suspended chord figure shows the score:
A suspended chord or sustained or sus chord is a three note chord. It is a triad in which the interval of a third is replaced by either an interval of a second to form a sus2 chord, or an interval of a fourth to form a sus4 chord.
The sus chord gets its unusual name from the use of a suspension in fourth species counterpoint. A suspension is a dissonant interval. The intervals of second and fourth are both dissonant intervals.
When a suspension occurs in functional harmony, the chord is treated as dissonant. The sus2 and sus4 chords are always treated as dissonant chords and must resolve to a consonant chord. There are three steps for resolving a suspended chord:
In a sus2 chord the interval of a second resolves to a third or to the tonic. In a sus4 chord the interval of a fourth resolves to a third.
Some writers of functional harmony only allow a suspended chord if it contains a perfect fourth and a major second or one of their inversions. By this definition, there is no Bsus4 chord, BEF, because it contains an augmented fourth, BF, and a minor second, EF.
It does not really matter how or whether a sus chord is resolved when writing pop harmony. It can be resolved in the same manner as in functional harmony, or it can be left unresolved as a standalone nonfunctional chord. A further interesting factor is that a sus chord can also be treated as an inverted quartal chord. This aspect is covered in more detail in the section on quartal harmony.
The sus chord has a lovely sound. An oenophile might describe it as distinctly open, with an airy bouquet, ambiguous tonality and a hint of dissonance.