Musicianship Resources

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Form in pop/rock music

This document is a glossary of terms and concepts that we will use in our analysis of pop/rock music. Terms, concepts, definitions, and notational guidelines in this document are taken either from common convention; the published or unpublished work of Jason Summach, John Covach, Walter Everett, Mark Spicer, or Daniel Harrison; or some combination thereof.

I. Text


A group of poetic feet. If the line is part of rhyming poetry, the last syllable/foot participates in a rhyme with another line. (Internal rhyme is also possible.)


A pair of lines. If poetry is rhyming, the two lines making up a couplet typically rhyme with each other. They may also participate in a larger rhyme scheme (see quatrain below).


A pair of couplets (i.e., four lines). Common quatrain rhyme schemes are aabb, abab, abcb.


A set of poetic lines that work together as a single narrative unit. Typically one or more quatrains (i.e., total number of lines are a multiple of four).

II. Formal Containers


A phrase is a musical unit that typically lasts for four bars and includes one line of poetry for its lyrical content. Phrases are designated by lower-case letters.


A module typically spans between 8 and 24 bars and includes 2–4 phrases. (Some auxiliary modules may contain a single phrase.) A module presents a single function (such as A, B, C, V, P, etc.) and presents a complete 2-, 3-, or 4-part pattern (see below). Modules typically set a stanza of lyrics (though occasionally a couplet). Modules are designated by upper-case letters according to function.

Module boundaries are also usually made apparent by poetic structure (end of a group of rhyming lines—couplet or stanza) or surface features of the song (clear rhythmic, harmonic, and melodic arrival; change in instrumentation or volume; return to beginning of a previously heard module; etc.).

All module definitions are based on Jason Summach's (2012) dissertation, "Form in Top-20 Rock Music, 1955–89."

Primary module

"A module that contains a song’s principal materials" (Summach, p. 322), such as the title text or the most memorable or climactic music. Primary modules exhibit strophe function (A) or chorus function (C). Formal cycles always end with the primary module for the song type (Summach, p. 50).

Secondary module

"A core module that directs attention towards or provides relief from the song’s primary modules” (Sumach, p. 322). Secondary modules exhibit bridge function (B), verse function (V), prechorus function (P), or postchorus function (Z).

Core module

Any primary or secondary module (Summach, p. 321).

Auxiliary module

A non-core module, such as I, J, O, or X (Summach, p. 321).


"The characteristic succession of modules in a song form, ending with the song’s primary module type” (Summach, p. 321). A cycle contains one or more modules, always in the same order (though sometimes with one or more modules omitted, especially toward the end of a song). A strophic song’s cycle is {A}. A 32-bar song’s cycle is {AABA}. A verse-chorus song’s cycle is typically {VC} or {VPC}. Curly brackets {} are used to refer to cycles (to differentiate them from names of song form types).

III. Formal functions

Functions for Primary Modules

Strophe (A)

The primary function of a strophe module is “to present the primary lyric and musical content and to provide a point at which the song might satisfyingly end” (Summach, p. 58).

In strophic form (AAA), strophes are the only core modules, and thus do not participate in a functional progression. Functional progression takes place on the phrase level within the strophe. The strophe modules themselves tend to set a stanza of text each with music that is self-contained and harmonically closed.

In 32-bar form (AABA), the strophe’s function as holding the primary text and music, and its function as being a stable point of departure and return, are elevated through contrast with the bridge module. In AABA songs, strophe function often involves the prolongation of tonic harmony. Strophes tend to be longer in strophic songs than in AABA songs (typically eight bars). In both forms, srdc is by far the most common internal pattern for strophes. For three-part strophes, the 12-bar blues progression is the most common pattern.

Chorus (C)

Chorus modules 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, p. 106). Choruses most frequently (but not exclusively) begin on-tonic.

Chorus modules are distinct from refrains primarily by virtue of their being modules in and of themselves, where refrains are contained within a module.

Functions for Secondary Modules

Bridge (B)

Bridge function shares many traits with the continuation function of classical form. Bridge modules 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 module (A or C) by contrasting with it and temporarily withholding it. A bridge module “must be followed by [the primary module] in order for its function to be satisfied” (Summach, p. 79), though it is possible for a bridge module in VC form to lead into a final verse module. Bridge modules tend to emphasize non-tonic harmonies and commonly end on dominant harmony. Bridges typically exhibit a two-part structure.

In VC songs, bridge modules are more free to contrast verse and chorus modules without a strong need to build expectation for the return of the chorus than in AABA form. In an AABA song, building expectation for the return of the strophe and arriving on dominant harmony in preparation of that return are essential to bridge function.

Verse (V)

Verse modules are lyric variant and contain lyrics that supply “narrative or emotional context” to the chorus text (Summach, p. 106). Until the 1960s, verse modules tended to be harmonically closed. Beginning in the 1960s, verse modules became more and more likely to be harmonically open (Summach, p. 114). Verses (like strophes) tend to begin on-tonic.

Verse modules tend to have two-part internal structures (unlike strophes).

Prechorus (P)

Prechorus function is most significantly typified in energy gain. Prechorus modules originate historically in the d (departure) section of an srdc pattern. (Think of an srdc strophe becoming longer until sr forms its own two-part verse module (or two successive verse modules), d forms its own prechorus module, and c forms its own chorus module.) As a result, prechorus modules bear many of the functional characteristics of d—fragmentation, acceleration of harmonic rhythm, and movement away from tonic harmony—and harmonic openness.

Postchorus (Z)

A short module that follows a chorus and serves only to close the cycle (not to introduce or transition to the beginning of the next cycle) has postchorus function (Mark Spicer 2011, par. 9).

Functions for Auxiliary Modules

Introduction & mid-song introduction (I)

Introductions tend to be short and untexted (i.e., instrumental) and tend to present musical material from one or more core modules to come. Introduction modules transition from the unmetered silence that precede the song to the musical activity of the first core module. This is often accomplished by the introduction of musical material in layers (e.g., one instrument at a time) or a more generic building of energy. Occasionally intros are incorporated that include non-core material. Such intros often correspond to an outro based on the same material, and together they create a “bookend” effect.

Multiple intro modules in a row based on different music are possible, and that option is more likely than to have no intro. Such a succession of intros would be labeled I1, I2, etc.

Mid-song intros function similarly, but in the middle of the song. They introduce the first module in the formal cycle.

Outro (O)

Outros function as a transition from song back to silence, and thus decrease energy. Often this is accomplished in the recording studio by way of a fadeout. (Even more often, no outro module is present, and the final core module brings the song to a close.) When an outro module is present, it is almost always based on material from the last core module that preceded it. Non-core outros tend to draw material from a non-core intro (the above “bookend” effect). “Rock songs almost always end with material that has been heard earlier in the song: either a core module, a core-based auxiliary module, or a reprise of the introduction” (Summach, p. 47). Outros exhibit closing rhetoric (see below).

Coda (X)

A coda is a “song-ending module that presents new material” (Summach, p. 47)—in other words, an outro not based on music previously heard. Like outros, codas exhibit closing rhetoric (see below).

Janus module (J)

A transitional passage that closes a preceding module and simultaneously introduces the next module is called a Janus module (a term Summach coined based on the name of the Roman god who simultaneously looks both backward and forward). Janus modules typically overlap with or elide the ending of the preceding module. J modules often function like mid-song introductions (with the added overlap/elision with the previous module).

Closing rhetoric

Closing rhetoric involves common patterns and techniques that signal that the end of the song is likely coming soon. Typical patterns and techniques include immediate repetition of a core module (except for the first core module) or part of a core module, thinning out of the texture, late-song intensification, fadeout, and bringing a previously harmonically open module to a point of harmonic closure. Closing rhetoric is typically found in outros, codas, and (most commonly) the last core module of a song.

Functions for Standout Passages Within Modules


“A lyric-invariant passage within a module that is otherwise lyric-variant” (Summach, p. 322). Like a climb (below), a refrain is too short to form its own module—typically a phrase or less. A refrain is most often the last line or so of a module’s text (tail refrain), and occasionally the material at the beginning of a module’s text (head refrain).


“A phrase with prechorus function, but of insufficient length to detach from the verse as a separate module” (Summach, p. 321). Always the last phrase of a verse module.

IV. Song-level structures

Strophic form (AAA)

A song form containing three or more formal cycles, where the formal cycle is {A}—that is, a single module exhibiting the function of a strophe. Auxiliary modules may also be present (I, O, J, or X). Strophic form is more common in early rock-and-roll (1950s–1960s) than in the 1970s and beyond. In Christian worship music, the influence of hymnody makes strophic form more common in contemporary music than in popular music (prominent examples include Keith & Kristyn Getty, Stuart Townend, and Bob Kauflin).

32-bar song form (AABA)

A song form containing at least one complete formal cycle of {AABA} (though typically two complete cycles or one complete cycle followed by a partial cycle). A is the primary module. Auxiliary modules may also be present.

AABA form can be realized as AABA, AABA’, AA’BA’, or AA’BA’’. No matter the degree of alteration of the main strophe, if the general functional progression of AABA is present, it is 32-bar/AABA form. 32-bar/AABA form was most common prior to the advent of rock-and-roll and disappears almost entirely from the Billboard top-20 after the mid-1960s. It’s most typical appearance has two four-bar phrases per eight-bar module, making the typical complete cycle 32 bars long, hence the common name 32-bar song form.

Verse-chorus form (VC, VCB)

A versatile song form that rapidly took over rock-and-roll in the 1960s and has dominated the genre ever since. A verse-chorus song’s formal cycle will contain at least two core modules—verse (V) and chorus (C), with the chorus module being the primary module. Other possible modules in the cycle exhibit prechorus (P), bridge (B), and postchorus (Z) functions.

A full cycle containing all modules except for B would be {VPCZ}. These four functions always progress in this order, though not all need be present. Bridge modules are somewhat flexible. If a song has single bridge module, it tends to appear once, followed by the last chorus, or the last prechorus and chorus, of the song. Bridges often appear in place of the verse and/or prechorus modules in the last cycle, not as an extra element. Thus, songs that incorporate all five core module types rarely will place all five in a single cycle.

Common non-bridge cycles include {VC}, {VPC}, and occasionally (especially as the first cycle in a song) {VVC}, with Z potentially added to the end of any. Common cycles including bridge are {BC} and {BPC}, with Z potentially added to the end of either.

Simple verse-chorus form

A term coined by John Covach referring to songs in verse-chorus form where the harmonic progression underlying the verse is the same as that underlying the chorus.

Super-simple verse-chorus form

A term coined by Jay Summach (based on Covach’s) referring to songs in verse-chorus form where the harmonic progression and the melody are both the same for verse and chorus (Summach, p. 322).

V. Module structures

Two-part (aa’)

A module is two-part when the phrases that make up the module can be grouped into a first half and a second half. In two-part modules, the second half is usually based on the same music as the first half, and thus it is labeled aa’. Often these two halves begin the same but have different endings, participating in an antecedent-consequent (weak → strong) relationship.

Two-part – ab

Very rarely a module’s phrases can be grouped into two clear halves based on different music. Such a module is labeled ab.

Three-part – aa’b

A module containing three phrases is a three-part module. If the first two phrases are based on the same music, the module is labeled aa’b (12-bar blues progressions are the most common example of a three-part aa’b module).

Three-part – abb’

If the second and third phrases in a three-part module are based on the same music, the module is labeled abb’.

Four-part – srdc

A module composed of four phrases often contains a sentential structure (presentation → continuation → cadential/conclusion). In pop/rock music, such a structure typically states a basic musical idea in the first phrase, restates it in the second, provides contrasting material in the third phrase (often employing fragmentation, acceleration of harmonic rhythm, and movement away from tonic harmony), and concludes in the fourth phrase either with a return to the basic idea and tonic harmony or with still newer material that forms a strong melodic, rhythmic, and harmonic conclusion. Walter Everett has called such a four-phrase sentential structure in pop/rock music srdc (statement, restatement/response, departure, conclusion).

In conventional lettering, an srdc module could employ an aaba structure (with statement material returning as a restatement and again as the conclusion), or aabc structure (where the conclusion material is new). Occasionally abcd or abca are possible, but only if b is a clear response to a, not simply new material.

srdc structures tend to divide neatly into halves: sr and dc.

VI. Harmony


A phrase or module is on-tonic when it begins with tonic harmony (I in root position).


A phrase or module is off-tonic when it begins on a harmony other than tonic.

Harmonically closed

A phrase or module is harmonically closed when it ends with tonic harmony (I in root position).

Harmonically open

A phrase or module is harmonically open when it ends on a harmony other than tonic.


The use of a non-tonic chord (usually dominant) at the end of a harmonically closed unit to transition into the beginning of the following on-tonic unit.

VII. Descriptors & rhetorical devices


A module or phrase is lyric-variant if each time it appears it brings (mostly) different lyrics.


A module or phrase is lyric-invariant if each time it appears it brings (mostly) the same lyrics. Lyric invariance tends to come at points of formal closure (tail refrains at the ends of strophes, choruses at the end of a verse-chorus song’s formal cycle).


A module or phrase is music-variant if each time it appears it brings (mostly) different music.


A module or phrase is music-invariant if each time it appears it brings (mostly) the same music.


Jay Summach uses the term “chorusification” (p. 321) to describe a process where modules are stripped away from the formal cycle until only the chorus module (C) remains. For example, a song that begins with the cycle {VPC} may appear near the end of the song without the verse {PC} and then again without the prechorus {C}. This process is part of a goal-directed progression toward the end of the song, giving special emphasis to the chorus.

VIII. Analytical Notation

Capital letters

Modules are labeled with capital letters according to function. A module that functions as a strophe is labeled with an “A”; a module that functions as a bridge, “B”; etc.

Lower-case letters

Phrases are labeled with lower-case letters according to their musical content. If two phrases use more-or-less the same musical framework (harmony, melody, and rhythm), they receive the same letter. Letters are assigned in the same manner as poetic rhymes: the first phrase is a and any phrase that follows based on the same music is also a (primes are used for slight variations, such as new text or altered instrumentation); the next phrase with new musical material is b; and so on. These letters do not correspond to functions.

The single exception to this convention is when phrases within a module demonstrate a sentential progression (srdc), in which case the first phrase (statement) is labeled s; restatement/response, r; departure, d; conclusion, c.

Full-sized numerals

Full-sized numerals are attached to capital letters when there are two or more modules with the same function but different music. For example, if a song contains two different melodies that both function as verse themes, they are labeled “V1” (the one that appears first in the song) and “V2.”

Subscript numerals

Subscript numerals are attached to capital letters when there are two or more modules with the same function and music but different text. For example, if a song contains three verses, and they all have different lyrics but the same music, they are labeled “V1”, “V2”, and “V3”.

Timeline notation

Variations Audio Timeliner does not support subscripts. Differentiate full-sized and subscript numerals in your written work. However, it is fine to use full-sized numerals for both purposes in your timelines.