Music Theory

Phrase Expansion

Phrase expansion is one of the most expressive tools composers have at their disposal. Various ways of expanding a phrase can heighten anticipation, toy with expectation, and lead a listener on a satisfying journey. Studying how composers expand phrases is important in interpreting their work and can enhance the creative work of composers in any genre.

Model Phrase

A model phrase sets up the expectation for phrase length, typically either four or eight measures. Usually phrase expansion is more readily perceived when the model phrase length has been clearly established. A phrase has been expanded when it is longer than the model length.

Phrase expansion occurs in two broad categories: external and internal.

External Phrase Expansion

External expansion occurs outside the main body of the phrase, either before the phrase begins, or after it ends. The two types are prefix and suffix.


A prefix is phrase expansion before the phrase begins. This is most commonly an introduction of some sort, before the appearance of a melody. The prefix may fulfill several important introductory functions, potentially setting up expectations for what is to come by establishing texture, tonal center, phrase rhythm, register, timbre, and other aspects.

In this Chopin prelude, the two-measure introduction is too short to be a phrase itself. Rather, it acts as a prefix to the following phrase, setting up several important aspects of the piece.

In Mozart’s Symphony No. 40, the prefix does a few things. The comparatively dark timbre of the violas signals the dark coloring of the movement to come. Tonal center and texture also get established. Interestingly, this prefix feels too short. Most prefixes are of a stabilizing length, like half the model phrase length. This one barely gets going before launching into the melody. It’s like starting a drive by going over a speed bump. Starting this symphony out with a speed bump feels like we’re being hurtled headlong into the action of the movement.

Prefixes can also appear in the middle of a piece.

This passage from Mozart’s Piano Sonata No. 16 shows the typical example. After a cadence, a prefix sets up the texture and tonal center before the melody of the next phrase enters.


A suffix is music that comes after the cadence, but is still part of the preceding phrase. This occurs either through repetition of the cadential device or through extension of the cadential harmony. Suffixes reinforce the importance of the harmonic and structural arrival.

In this passage, also from Mozart’s Piano Sonata No. 16, the PAC in m. 71 extends by repeating the V-I harmony over the course of the next three measures.

In Chopin’s Prelude No. 3, the suffix consists of an extension of the final harmony. It serves to reinforce the harmonic arrival, release the tension built up during the piece, and give us a soft landing.

In this piece, Satie uses our cultural affinity for dramatic concluding suffixes to comedic effect.

As with prefixes, suffixes can happen in the middle of a piece.

Internal Phrase Expansion

Internal phrase expansion occurs in the main body of the phrase, after the melody has come in and before the cadence. The five types are echo repetition, sequential repetition, deceleration, parenthesis, and cadential evasion.

External phrase expansion may be easier to identify visually than internal phrase expansion. To identify expansion, first identify all cadences, then count the number of measures in each phrase (example given forthwith).

Normalizing an expanded phrase is the process of removing the material causing the expansion. Normally, an expansion has occurred only if the phrase can be normalized by removing material.

Echo Repetition

Echo repetition is the immediate repetition of a portion of the phrase, sometimes in a different octave or different voice.

In Schubert’s Moments Musicaux No. 3, the model phrase length is eight measures. The phrase beginning at m. 59 is expanded through echo repetition: measures 66 and 67 are echo repetitions of m. 65. This phrase could easily be normalized by removing mm. 65-66. (Notice the long suffix from m. 68 to the end.)

Sequential Repetition

Sequential repetition is the immediate repetition of a portion of the phrase at a new pitch level.

In Handel’s Suite in F Minor, the sequential repetition (under the blue bubbles) pushes the four-measure model out to six measures.


Deceleration is a composed-out ritardando, in which note values are longer than they were in the model phrase.

In this Brahms setting, the model phrase length of four measures gets expanded by one measure due deceleration: the two measures under the blue bubble can be normalized down to one measure by making each melodic note a quarter note. This is most commonly seen at the end of pieces (slowing things down) but can also be seen in the middle of a piece.


Parenthesis is the insertion of unrelated material within a phrase. This insertion is accompanied by some rupture of the musical fabric, such as abrupt changes in register, texture, harmony, or some other aspect.

In this instance, the rhythm and meter take a dramatic turn, upending the listener’s expectations. The bracketed passage could simply be removed – but it’s so much more fun to leave it in!

Cadential Evasion

Cadential evasion is when everything is prepared for the arrival of a cadence (and you just know it’s coming!), and then the cadence never happens, usually because of some type of deceptive resolution.

In this Schubert piano sonata, the drive toward a cadence may sound fulfilled at the first red arrow, but the soprano is in the wrong register, and the dynamic marking creates a disruption. The second red arrow is even less satisfying. The two-times evasion increases the listener’s anticipation for the eventual satisfying resolution.