Irregular resolution

In music, an irregular resolution is resolution by a dominant seventh chord or diminished seventh chord to a chord other than the tonic. Regarding the dominant seventh, there are many irregular resolutions including to a chord with which it has tones in common or if the parts move only a whole or half step.[2] Consecutive fifths and octaves, augmented intervals, and false relations should still be avoided.[2] Voice leading may cause the seventh to ascend, to be prolonged into the next chord, or to be unresolved.[3]

Irregular resolution Type I Play . Two common tones, two note moves by half step motion.
Irregular resolution through augmented sixth equivalence Play .[1] One common tone, three notes move by half step motion.

The following resolutions to a chord with tones in common have been identified:

  • Type I, in which the root motion descends by minor third. C, E, G, B would resolve to C, E, G, A; two tones are common, two voices move by half-step in contrary motion.
  • Type II, in which the root motion rises by minor third. C, E, G, B would resolve to D, E, G, B; again, two tones are common, two voices move by half-step in contrary motion.
  • Type III, in which the root moves a tritone (two minor thirds) away. C, E, G, B would resolve to C, E, F, B = A; again, two tones are common (with enharmonic change), two voices move by half-step in contrary motion.
Regular resolution Play . One common tone, two notes moves by half step motion, and one note moves by whole step motion.

Type I is common from the 18th century; Type II may be found from the second quarter of the 19th century; Type III may be found from the mid-19th century. The composer Richard Edward Wilson is responsible for the categorization.

The most important irregular resolution is the deceptive cadence,[3] most commonly V7–vi in major or V7–VI in minor.[1][3] Irregular resolutions also include V7 becoming an augmented sixth [specifically a German sixth] through enharmonic equivalence[1] or in other words (and the adjacent image) resolving to the I chord in the key the augmented sixth chord (FACD) would be in (A) rather than the key the dominant seventh (FACE) would be in (B).