cadence
cadence, in music, the ending of a phrase, perceived as a rhythmic or melodic articulation or a harmonic change or all of these; in a larger sense, a cadence may be a demarcation of a half-phrase, of a section of music, or of an entire movement.
The term derives from the Latin cadere (“to fall”) and originally referred to the stepwise descent of the tenor part, associated with formal endings in certain types of late medieval polyphony. A typical cadential formula of this period is the Landini cadence, so called because of its frequent appearance in the music of the 14th-century composer Francesco Landini—although other composers of the time used the cadence as well.
With the emergence of tonal harmony based on chord and key relationships during the 17th century, the cadence assumed greater structural importance, especially in homophonic, or chord-based, music with regular phrases. In such music, the cadence can be regarded as analogous to the rhyme at the end of a line of metric verse. Four principal types of harmonic cadence are identified in common practice: usually these are called authentic, half, plagal, and deceptive cadences.
In an authentic cadence, a chord that incorporates the dominant triad (based on the fifth tone of the scale) is followed by the tonic triad (based on the first tone of the scale), V–I; the tonic harmony comes at the end of the phrase. In the strongest type of authentic cadence, called the perfect cadence, the upper voice proceeds stepwise either upward from the leading tone (seventh degree of the scale) or downward from the second degree to the tonic note, while the lowest voice skips from the dominant note upward a fourth or downward a fifth to the tonic note. Other arrangements of this harmonic formula—for instance, with the leading tone in an inner part (e.g., the alto or tenor voice in four-part harmony)—are considered less perfect because they are perceived by the listener as less final.
The half cadence ends the phrase on a dominant chord, which in tonal music does not sound final; that is, the phrase ends with unresolved harmonic tension. Thus a half cadence typically implies that another phrase will follow, ending with an authentic cadence.
In the plagal cadence the subdominant (IV) triad leads to the tonic (I). This cadence usually is an extension to an authentic cadence, and its most characteristic and formulaic usage in the West is with the final amen (IV–I) at the end of a hymn in Christian churches.
A deceptive cadence begins with V, like an authentic cadence, except that it does not end on the tonic. Often the triad built on the sixth degree (VI, the submediant) substitutes for the tonic, with which it shares two of its three pitches. A deceptive cadence may be used to extend a phrase, to overlap one phrase with another, or to facilitate a sudden modulation to a remote key.
A cadence may also mark the beginning of a phrase or section, for instance after a dominant pedal point (in which the dominant note is sustained under changing harmonies). When one phrase ends fully in the dominant harmony and the next begins in the tonic, the music has incorporated the cadential structure as an articulative device. Such a technique is a variant of the authentic formula.
In monophonic music (consisting of a single line of melody) such as plainsong, certain melodic formulas imply a cadence. The melodic styles of a culture frequently prescribe the proper final note of a melody and how to approach it. Certain rhythmic patterns may be recognized as indicators of cadence, as in some Japanese music. Colotomic structure, the systematic use of prescribed instruments at fixed rhythmic intervals, may also signal cadence—e.g., in Indonesian gamelan—as the recognized pattern approaches its end.