A cadence is a sequence of at least two chords that brings an end to a phrase, either in the middle or at the end of a composition. It is a chord progression that "feels" like a conclusion. Cadences are the musical equivalent of punctuation, such as commas or periods, in speech or writing. They are often indicated by a couple of Roman numerals indicating the root (note on which a triad is built) of the two triadic chords that make up the cadence.
Four types of cadence are especially common and have been given special names. Two end on the tonic chord – the perfect cadence (or full close) and the plagal cadence; and two which are only used at intermediate points – the imperfect cadence (or half close) and the interrupted cadence. The four main types of cadence are:
See below for examples of these different types of cadences.
To any of the dominant chords mentioned above, the seventh may be added. Any of the chords may be taken in inversion, but if that is done in the case of the perfect cadence its effect of finality (i.e., its "perfection") is lost.
A deceptive cadence is a chord progression that seems to lead to resolving itself on the final chord, but does not. Specifically, harmonic motion of the five chord moving to six in the major tonality.
Also called a full close, a perfect cadence uses the chord sequence V-I, or V7-I. It is the most complete sounding of all the cadences because the dominant (V) chord, or dominant 7th, is the one that leads most powerfully to the tonic chord. One of the reasons for the dominant chord's special power is to be found in acoustic considerations – the fifth being the next harmonic after the fundamental note and its octave. The other is the presence of the leading note of the scale. It is a fact of melody that the leading note, as its name implies, has a tendency to move up a semitone to the tonic. Consequently, the essential elements in a perfect cadence are a move from the dominant to the tonic in the bass, and above the bass a move from the leading note to the tonic.
The move from leading note to tonic can be at the top or in the middle of the chords, although the feeling of finality is stronger when the music ends the tonic in the melody as well as in the bass. The dominant seventh chord prepares the tonic even more powerfully because of the need for the dissonant interval of the seventh to be resolved.
A cadence in which the dominant (V) chord leads the listener to expect a tonic chord (and hence a perfect cadence) but is in fact followed by any chord except the tonic. Often the final chord is the submediant chord (VI).
Also called a half close, a cadence that ends on the dominant chord (V). Various chords can be used to precede the dominant: I, II, IV, and VI are all common.
A cadence that uses chords IV-I, i.e., the subdominant chord followed by the tonic chord. Its effect as a final cadence is less compelling than that of the perfect cadence since IV is less powerful than V as a preparation for I, lacking as it does the leading note with its push toward the tonic. In the 16th century the plagal cadence was used to end pieces much more frequently than it has been since, though it is frequently found at the end of hymns.
This cadence is found only in the minor key. It uses the chords IVb-V, and is really an imperfect cadence in the minor key.