Motives, Phrases, and Phrase Groupings

Chapter 3:  Phrase Groups

Two phrases normally form a period, given that the first phrase (antecedent) ends with a less conclusive cadence than the second phrase (consequent).  The phrases may be melodically similar (parallel) or dissimilar (contrasting).  They may be of equal length to create a symmetrical period, or of different lengths creating an asymmetrical period.  Occasionally, a period consists of more than two phrases.  If the final harmonic cadence is not more conclusive that the earlier one, combined phrases are referred to as a phrase group rather than a period, even though they function together as a unit.

Musical example of a Contrasting  Period

 Diagram of the Contrasting Period

The example above shows a symmetrical period with a Half Cadence ending the first phrase, and a Perfect Authentic Cadence ending the second phrase. In some cases phrases are connected with short linking material, which expands a period.  In other cases, the end of the first phrase is fused with the next, creating an elision in which the end of the first phrase is the beginning of the second phrase.