- Analyzing musical form involves determining the identity and function of musical spans.
- Musical sections are either or .
- Core sections are either or .
- Auxiliary sections are either or .
Overview of Formal Sections in General
Understanding the form of a musical work typically involves breaking it down into spans of time, based on how each span is similar to and/or contrasts with other spans. These spans are then classified based on the identity of their musical material and how the section “functions” in the context of the piece. The two largest categories of formal function are core sections and auxiliary sections. below summarizes the hierarchical relationship between some of the most common section types. At the broadest level, musical sections are either or . Core sections are either or , and auxiliary sections are either or .
The core sections identified intypically introduce and repeat a work’s primary musical content. You can think of them as the sections you might sing for someone if they asked you how the work “goes.” You can also think of core sections as containing the work’s themes, though the term “theme” can be used in a broad or specific sense. Core sections also tend to repeat, which is another reason they will often make a stronger impression on your memory.
Main sections are typically the first section that presents primary musical content; they are usually repeated later in the work and are characterized by a relative sense of stability.
The terms for main sections change depending upon the conventions of the genre and form (if it is a form with a name). When thinking about form in general, the main section should be called A, but within a known form, it may go by many names, including but not limited to:
- (rondo or verse-refrain)
- theme from a set of variations
- (AABA and strophic)
Contrasting sections are hard to generalize, since they can vary in affect and stability. In some cases, the section is perfectly stable, and it contrasts mainly because it comes second instead of first; in other cases, a contrasting section may be the most unstable section of the work.
Unstable contrasting sections may share many musical features with (defined below). The distinction lies in whether or not it is considered a core section: contrasting sections sound like a primary place in the work, whereas connective sections sound like a place between two core sections. In cases where the line between the two is blurry, a decision can be made based on the conventions of the overall form of the piece, or multiple formal descriptors (e.g., ) can be used to create an accurate and unforced classification.
Formal stability is the sense of tension vs. calmness in a portion of music. A relative sense of stability in a work is a common means of delineating form, and it is an important dramatic concern for creating momentum and engaging a listener’s expectations about what might happen, given their familiarity with how other pieces in a given genre/style behave.
Common features for each might include some combination of the following, among others:
- Stability: relatively less change, consistent or decreasing dynamic level, tonic expansions, regular , no , diatonic melody, and diatonic harmony
- Instability: relatively more change, increasing dynamic level, extreme registers, increased chromaticism (tonicization), increased rhythmic activity, modulation, sustained dominant, (especially chromatic ones), irregular hypermeter, and irregular phrase lengths
Because it’s statistically common for works to start with a stable section, an unstable contrasting section would likely sound unusual at the beginning of a work.
In terms of form in general, the first contrasting section is labeled B, and each subsequent new section receives the next letter of the alphabet (C, D, E, etc.).Within a known form, contrasting sections go by many names, including but not limited to:
Auxiliary Formal Sections
In addition to the sections of a work, other sections may introduce, follow, or come between these core sections. These sections are called , and there are two general categories: and .
External Auxiliary Sections
External auxiliary sections either introduce a piece/section () or follow the generic conclusion of the piece or section (). Prefixes and suffixes come in small and large varieties.
A prefix (Rothstein 1989) refers to music that comes before the generic start of a phrase or piece and tends to express a formal sense of “before the beginning.” A prefix can be described as either small or large depending on whether or not it contains a complete . Large prefixes contain at least one phrase, while small prefixes don’t have complete phrases and are typically far less noticeable. Small prefixes are often nothing more than the accompaniment for a section starting before the melody begins, and they may precede any phrase in a work.
The most common type of large prefix is called an . Introductions are often in a slower tempo than the rest of the work and often contain their own thematic material. Small prefixes can be found in works of most genres and eras, but large prefixes are less ubiquitous and tend to show up more often in particular genres, like the opening of a symphony. However, other genres like the piano sonata (Beethoven’s “Das Lebewohl,” Op. 81a), string quartet (Mozart’s “Dissonance” quartet), and dance forms like ragtime (Joplin, “The Entertainer”) can contain them as well.
Below are some examples:
- Small Prefix:
- Large Prefix:
- Introduction of the 1st movement of Mozart’s “Dissonance” string quartet in C major (K. 465) – The whole movement is about 10 minutes long, and its slow introduction (large prefix) lasts for nearly two minutes until the sonata form proper starts. There is a stark tempo change from slow to fast at 1:59 that makes the boundary clear.
- Joplin’s “The Entertainer” – First four measures
- Madonna’s “Vogue” – This large prefix has many subsections (0:00, 0:34, 0:50), but the song proper doesn’t start until she begins singing at 1:07.
A suffix (Rothstein 1989) refers to music that comes after the close of a phrase or piece and tends to express a formal sense of “after the end.” The distinction between large and small again concerns whether or not it contains a complete . Small suffixes can be found after the close of any phrase, but the affect is quite different depending on the type of cadence they follow. After an authentic cadence, they typically project a sense of stability and closure, but after half cadences, they tend to prepare for the entrance of the upcoming section and therefore project a sense of instability. Though possible after any phrase, large suffixes typically appear in two specific locations: (1) at the very end of a piece in the form of a , and (2) as the closing section of a sonata form’s exposition and recapitulation (see Sonata Form). In most cases, a suffix contains musical material that is different from the phrase it follows, though that material may be derived from an earlier phrase.
Below are some examples:
- Small Suffix:
- Dove Shack’s “Summertime in the LBC” – After the final chorus, a small prefix (in the form of a simple accompaniment) ends the song as it fades out from 3:41 until the end.
- Bizet, Habanera from Carmen – The B section ends just after the singer sustains a high note and cadences with the orchestra immediately after (cadence is at 2:01). After this cadence, the orchestra just repeats an accompanimental pattern a few times. The music from 2:01-2:06 is the small suffix.
- Large Suffix:
- Puccini, “O Mio Babbino Caro” from Gianni Schicchi – Ending: You can hear the formal ending of the aria at 1:48 with the line “O Dio, vorrei morir!” at which time the aria could have ended satisfactorily. However, an elision occurs with the strings, which play the main melody (a.k.a. ritornello) after the soloist finishes her line. Notice that the music from 1:48 to the end projects a sense of stability, as suffixes tend to do when they follow an authentic cadence.
- End of the 1st movement of Mozart’s “Dissonance” string quartet in C major (K. 465) – This movement ends with a coda at 9:58 (large suffix at the very end of a piece). Notice that it starts after the material from the closing section of the recapitulation comes to an end. You can compare the very end of the exposition (6:12) to the very end of the recapitulation (9:28) to hear how this large suffix is added material that was not in the exposition (even though many of its motives and ideas have been heard before).
- Brahms’s Intermezzo in A major, op. 118, no. 2 – This work is in ternary form. The A section ends at 1:28 and is followed by a suffix from then until before the B section starts at 1:57.
Connective Auxiliary Sections
Generally, a transition is a section of music that functions to connect two sections. Transitions usually help to lead away from the piece’s main section toward a contrasting section. In particular, a transition comes between two sections where the upcoming section is not the initiation of a large-scale return (i.e., between A and B, not between B and A). Often a is introduced to help prepare a section in a new key, though it is not required. A transition also plays a role in the balance of stability and instability in a work. Core sections of a work are very often stable thematic statements (relatively), but transitions typically introduce instability (and a gain in energy), which will likely be countered by the stability of the section that follows.
Like suffixes and prefixes, transitions and (discussed further below) come in “large” and “small” varieties. A transition can be described as either small or large depending on whether or not it contains a complete . Large transitions contain at least one phrase, while small transitions don’t have complete phrases and are typically far less noticeable.
Near their end, transitions (and retransitions) often drive toward attaining the of the upcoming key. Often, a suffix will begin once the dominant has been attained in a situation sometimes called “standing on the dominant” (William Caplin) or “” (James Hepokoski and Warren Darcy).
A transition may have a clear stopping point before the next section starts, or there may be a single melodic line that fills the space between it and the upcoming section (), or the transition my end at the onset of the new section with an . In more vague cases, the end of the transition and the start of the new section may be hard to pinpoint, but it is still clear that it must have happened during a particular span of time.
Transitions are commonly found in sonata forms between the and and in rondo forms between the A section () and a contrasting section (). Small transitions are often found in to connect the A and B sections.
Below are some examples:
- Large Transition:
- Mozart’s piano sonata in B♭ major, K. 333, 1st – This work is in sonata form. The transition between the primary theme and the secondary theme occurs between 0:20 and 0:42.
A retransition is very similar to a transition, but its location and function are different. Retransitions come between two sections where the upcoming section is the initiation of a large-scale return (i.e., between B and A, not between A and B). In most cases, retransitions help to prepare the return of the piece’s : the return of the A section in ternary or rondo form, or the restatement of the at the onset of the in sonata form. A retransition often drives toward attaining the dominant chord of the home key and will often prolong the dominant once attained, usually in the form of a . Retransitions may have a clear half-cadential ending (possibly followed by a suffix), or they may have an ending that coincides with the initiation of the following section.
Below are some examples:
- Small Retransition:
- Chopin’s Polonaise in C minor, Op. 40, no. 2 – This work is in compound ternary form. In the first, large A section of the overall ABA form, there is a small retransition between B and A from 2:35 to 2:39. It is only one measure long.
- Handel’s aria “Lascia ch’io pianga” from Rinaldo – This work is in five-part rondo form (ABACA). There is a very short, small retransition between the B and A sections from 1:41 to 1:44.
- Large Retransition:
- Mozart’s piano sonata in B♭ major, K. 333, 1st – This work is in sonata form. The retransition between the development and the recapitulation occurs between 4:29 and 4:45.
- Brahms’s Intermezzo in A major, Op. 118, no. 2 – This work is in ternary form. There is a retransition between the B section and the final A section from 3:08 to 3:19.
- Rothstein, William. 1989. Phrase Rhythm in Tonal Music. New York: Schirmer.
- Summach, Jason. 2012. “Form in Top-20 Rock Music, 1955–89.” PhD diss., Yale University.
- This particular dichotomy was introduced by Jay Summach (2012). ↵
Core sections comprise the main musical and poetic content of a song. Core sections include strophe (AABA and strophic form only), bridge, verse, chorus, prechorus, and postchorus.
Sections that introduce, follow, or come between a work's core sections (A, B, primary & secondary themes, refrains, episodes, and developments/digressions/contrasting middles). Auxiliary sections are either external or internal. External Auxiliary Sections either introduce a piece/section (prefix) or follow the piece's/section's generic conclusion (suffix). Prefixes and suffixes come in small and large varieties. Internal auxiliary sections (connective sections) function to connect two core sections. Transitions generally help lead away from the piece's main section toward a contrasting section (B, secondary theme, episodes, developments/digressions/contrasting middles), and retransitions generally help to lead back to the piece's main section (usually A or a sonata form’s primary theme).
A section that presents the work's primary musical ideas. Usually, the main section is the first core section of the work. Examples include primary themes, refrains, expositions, choruses, or strophes.
A core section that provides contrast with the main section. May be stable or unstable.
A category of auxiliary sections including prefixes (which introduce a piece/section) and suffixes (which follow the generic conclusion of a piece/section).
A category of formal sections that connect two core sections; for example, transitions and retransitions.
The main section of a sonata-form work, in the tonic key. P themes are usually stable.
In a rondo form, a refrain refers to the work's primary theme. It is often referred to as a refrain because of its recurrent nature. In most rondos, the refrain is stated at the beginning, restated after each contrasting episode, and then one more time as the last form sectional, though a coda may follow.
The first large section in a sonata form work. It usually establishes the main themes of a work and sets up a conflict that is later resolved in the work. This conflict often takes the form of differing key centers (such as when the primary theme of a sonata is in tonic and the secondary theme is in the dominant)
Chorus sections are lyric-invariant and contain the primary lyrical material of the song. Chorus function is also typified by heightened musical intensity relative to the verse, including features like “a more dense or active instrumental texture; prominent background vocals; and/or a higher register melody” (Summach 2012, p. 106). Choruses most frequently (but not exclusively) begin on-tonic.
Chorus sections are distinct from refrains primarily by virtue of their being sections in and of themselves, where refrains are contained within a section.
An intensified version of the chorus that retains the same harmony and contains the hook of the song, which increases memorability for the audience, and encourages dancing.
A basic multi-phrase unit. In pop music, a strophe is a focal module within strophic-form and AABA-form songs.
The process of becoming is an analytical phenomenon that captures an in-time, analytical reinterpretation regarding a formal/phrasal unit's function. In this situation, a formal/phrasal label at first seemed fitting, but as that unit continues in time, a different label seems fitting. Even upon re-listening, this process of conversion is likely to still be experienced. The rightwards-double arrow symbol (⇒) is often used to denote this process. Examples include, primary theme ⇒ transition, continuation ⇒ cadential, suffix ⇒ transition, and any number of other combinations.
Groupings of measures into different patterns of accentuation
A change of key.
In the Classical-era of western, classical music—which spans the middle to the end of the 18th century—there were a specific set of standard modulation schemes that were used within a section of music. These are summarized below:
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A pattern that is repeated and transposed by some consistent interval. Usually the term "sequence" refers to both the melody and harmony being transposed by the same interval, but we can also speak of "melodic sequences" or "harmonic sequences" where only one domain participates.
The contrasting section of a sonata-form work. The S theme begins and ends in a contrasting key (usually V in major-mode sonatas and either III or v in minor-mode sonatas). S themes are usually stable.
A term used when describing the sections of a rondo form that are not the main theme (a.k.a. A or refrain). Episodes provide contrast with the main theme through changes in multiple domains, primarily key and melodic/rhythmic/harmonic material.
Verse sections are lyric-variant and often contain lyrics thatadvance the narrative. Until the 1960s, verse sections tended to be harmonically closed. Beginning in the 1960s, verse sections became more and more likely to be harmonically open (Summach, p. 114). Verses (like strophes) tend to begin on-tonic.
A section of a sonata form that is unstable, and which may or may not explore thematic material established in the exposition.
Bridges tend to play a transitional role (neither the point from which to depart, nor the point of arrival) in the formal cycle, generating high expectation for the return of the primary section by contrasting with it and temporarily withholding it. Bridge sections tend to emphasize non-tonic harmonies and commonly end on dominant harmony.
A core section is formal category including both main sections (e.g., A, primary theme, refrain) and contrasting sections (e.g., B, C, D, secondary theme, episode, contrasting middle, development, digression). In contrast to auxiliary sections, core sections present the main musical material of a work and generally represent the bulk of a composition.
An external expansion that occurs before the beginning of a phrase. Prefixes are usually introductions, and they may be small, as when the accompaniment for a lied begins before the singer, or they may be large, as when a symphony begins with a slow introduction.
A type of external expansion that occurs after the end of a phrase. There are three terms we commonly use to describe suffixes, ranging in size from smaller to larger: post-cadential extension, codetta, and coda.
A relatively complete musical thought that exhibits trajectory toward a goal. In much music, that goal is a cadence; so we might also say that a phrase is a relatively complete musical thought that ends with a cadence.
A section of music that occurs before the start of the musical form proper. In faster movements, introductions tend to have noticeably slower tempi. Introduction can range considerably in length, ranging from less than a single phrase (small prefix) to one or more phrases (large prefix). In the 18th century, introductions often contained independent musical material that doesn't appear in the rest of the work proper, but in the 19th century, composers tended to explore the integration of the introduction's material with the rest of the work.
A type of suffix (external auxiliary section). Codas are usually of the large variety (a phrase or longer), and they occur at the end of a work (or end of a movement within a multi-movement work) after the PAC that ends the piece proper. The word coda is Italian for “tail” because they are found at the tail end of a work. Sometimes composers communicate the location of the coda by writing the word in the score but this is not necessary to identify a section as a coda. Like all suffixes, codas are considered an expansion technique and therefore the are not essentially to the structural content of the work and it is often said that the work would still make complete syntactic sense if it were removed entirely.
A retransition is very similar to a transition but its location and function are different. Retransitions come between two sections where the upcoming section is the initiation of a large-scale return. In most cases, retransitions help prepare the return of the piece’s main section. In a ternary form this would be the A section, in a sonata form this would be the restatement of the primary theme at the onset of the recapitulation, and in a rondo this would be the return of the refrain (a.k.a. the A section). A retransition often drives toward attaining the dominant chord of the home key and will often prolong the dominant once attained, usually in the form of a suffix. Retransitions may have a clear half-cadential ending (possibly followed by a suffix), or they may have an elided ending that coincides with the initiation of the following section.
A category of chords that provides a sense of urgency to resolve toward the tonic chord. This cateogry of chords includes V and viio (in minor: V and viio).
Extensive prolongation of the V chord. Also known as "standing on the dominant." Often involves a pedal point on sol (5̂).
Caesura fill is when a single voice of the musical texture bridges what would otherwise be a gap between two sections.
An elision is the overlapping of two phrases that functions as the ending of one phrase and the simultaneous beginning of the next.
A musical form consisting of three distinct sections, in an ABA (not ABC) formal structure. The B section typically contains contrasting material in a new key. Repeat signs around each section are common.
A section of a sonata form work that beings back themes from the exposition and which resolves the conflict established in the exposition.