How cadences are classified · Harmonic functions · Music theory
Popular harmony classifies cadences by the chords they use: dominant, V – I; subdominant, also called plagal, IV – I; and compound, IV – V – I, with II…
How cadences are classified
Popular harmony classifies cadences by the chords they use: dominant, V – I; subdominant, also called plagal, IV – I; and compound, IV – V – I, with II instead of IV in its most usual form, II – V – I. That last one is the commonest formula in all of jazz.
Each can also end on the tonic, in which case it is authentic, or on one of its substitutes, in which case it is deceptive: V – VI is the best known. And its other chords can have substitutions or alterations: the minor subdominant, IVm – I, has its own color, very common in ballads.
The same thing, other names
Classical analysis speaks of perfect, imperfect, plagal, deceptive and half cadences, according to how conclusive they are, as in the lesson on the chords of the key. The two classifications do not contradict each other: one looks at which chords take part, the other at the effect on the phrase. In both, V – VI is deceptive and IV – I, plagal.