Composers organize chords in specific combinations to signal the conclusion of musical passages. These points of repose are known as cadences. Furthermore, composers frequently embellish chords with nonchordal pitches known as nonharmonic tones. This chapter is devoted to these two fundamental elements of musical composition.
Phrase
A phrase is a substantial musical thought, which ends with a musical punctuation called a cadence. Phrases are created in music through an interaction of melody, harmony, and rhythm. The first part of this chapter concentrates on the harmonic and rhythmic aspects of phrases; in Chapter 6 we will take up the melodic aspects.
Harmonic Cadence
A harmonic cadence is musical punctuation that closes a phrase or section of music. Cadences differ considerably in musical strength. Some signify the end of a complete musical thought and can be compared to the period (.). Others bring an incomplete idea to a close but suggest something else to come. These can be compared to a comma (,) or a semicolon (;). Most cadences conclude with either the V or I chord. The dominant frequently appears as a seventh chord (V7).
Perfect Authentic Cadence
The perfect authentic cadence is a progression from V to I in major keys and V to i in minor keys. Both chords must be in root position. In this cadence the tonic note must also be the highest sounding pitch in the tonic triad. From the standpoint of finality, the perfect authentic cadence is the strongest cadence of all.
Imperfect Authentic Cadence
The imperfect authentic cadence is slightly weaker than the perfect authentic cadence. A perfect authentic cadence becomes imperfect when: 1. The highest-sounding tone in the tonic triad is a tone other than the tonic note. 2. The viiø triad is substituted for the V, making the cadence viiø 6 to I or viiø 6 to i. 3. One or both of the chords (V or I) is inverted. Examples are: V6 to I or V to i6.
Half Cadence
If the second chord of a cadence is V, it is a half cadence. This permits a large number of possibilities, but composers actually employ only a few. I to V, IV to V, or ii to V account for the vast majority of half cadences. A half cadence from iv6 to V in a minor key is sometimes called a Phrygian half cadence.
Plagal Cadence
The plagal cadence is nearly always one progression: IV to I in major keys, or its equivalent, iv to i in minor keys. Infrequently, the progression ii6 to I occurs as a plagal cadence.
Deceptive Cadence
If the first chord is V and the second is not I, the cadence is deceptive. Although there are a large number of possibilities, composers most often select vi (VI in minor).
Rhythmic Cadence
Phrase endings often contain characteristic rhythmic patterns that create a rhythmic cadence. Notice in Figure that the phrase ending can be sensed by tapping the rhythm alone.
Rhythmic cadences often end with a longer note than the prevailing note values or are followed by a rest, which, in effect, lengthens the final note. A rhythmic cadence pattern may recur several times throughout a given composition,
Phrases can exist at the rhythmic level alone, independent of harmony and melody. Drum cadences, for example, are clear examples of rhythmic phrases.
History
The history of harmonic cadences is interesting because so many early cadence types now sound quaint and unfulfilling. Prior to the baroque period and the establishment of functional harmony, cadences were considered simply a manipulation of melodic lines that converged or diverged to a point of rest, usually the final (the first degree of a mode). The following are typical of early cadences.
The advent of the baroque period with its tonality and functional harmony brought about the familiar cadence types.
The standard cadences (authentic, half, plagal, and deceptive) continued with little change from the baroque period throughout the classical period.
Cadence types remained virtually unchanged during the romantic period, but composers sometimes decorated their cadences in a more florid manner. In the post-romantic and impressionistic period, some cadences were simply highly decorated (and often camouflaged) traditional cadences. Others resembled a return to the linear cadences of the prebaroque.
During the contemporary period, the idea of cadence formulae (distinct types such as authentic, half, etc.) became nearly extinct. Some composers of atonal (no tonal center) music employed interpretation markings (crescendo, loud dynamics, etc.) effectively to bring their compositions to a close. Others, in an effort to avoid stereotyped cadences, chose to allow their compositions to come to a halt without any hint of cadence.
Jazz and popular music frequently include traditional cadences similar to those studied in this text, but often disguised with substitutions and decorations. During the third quarter of the twentieth century, some creative jazz artists adapted free-tonal and atonal techniques to suit their improvisational styles. Free-tonal style permits free use of all 12 tones of the octave but maintains a tonal center. Atonal music contains no tonal center whatsoever. Figure below shows some traditional cadences that have been decorated.
In Figure (a) the dominant (V) is decorated with an eleventh and the tonic contains an added interval of a sixth above the bass note. In (b) the tonic chord contains the intervals of a sixth and a ninth above the bass note. In (c) the tonic chord contains a thirteenth (an octave plus a sixth) above the root.
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