Melodic Form: Phrases and Sentence Form
A phrase is a substantial musical thought that ends with a cadence. For a review on cadences, see text Chapter 6.2. Phrases are created through the interaction of melody, harmony, and rhythm. Though they can be any length, phrases are often are 4, 8, or 16 bars long. Phrases can be sometimes combined into larger phrase groups and structures, and can sometimes be divided into smaller phrase segments.
Brackets are used to divide and mark phrases in a musical score. We label each phrase or segment with lower case letters to show their melodic relationship to one another.
Phrases can be an exact repetition: aa
Phrases can be varied so that they are repeated with modifications and embellishments: aa’
Phrases can also be contrasting so that they use different melodic material: ab
Sentence form is a specific type of form within a phrase. In order to form a sentence, a phrase will have two halves. The first half consists of a statement (a) and a repetition of that statement at a different pitch level (a’). The second half consists of contrasting melodic material that concludes the phrase with a cadence (b). Sentences in music sound like conversations. Someone says something (a), someone comments on it (a’), and someone concludes the ideas (b).
Look and listen to these examples of sentence form.