A cadence is the characteristic way in which a musical phrase, section, or entire piece of music comes to a close. This feeling of a natural ending is called cadence. The longer you take to reach this point of cadence, the more tension you can build in your music.
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. In these instances, you’re setting up an unresolved tension, typically by ending on the V (dominant) triad. A perfect authentic cadence becomes imperfect when:
- The highest-sounding tone in the tonic triad is a tone other than the tonic note.
- The viio triad is substituted for the V, making the cadence viio6 to I or viio6 to i.
- One or both of the chords (V or I) is inverted. Examples are: V6 to I or V to i6.
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.
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.
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).
Phrase endings often contain characteristic rhythmic patterns that create a rhythmic cadence. 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.