Analyzing musical form involves determining the identity and function of musical spans.

Musical sections are either core or auxiliary.

Core sections are either main or contrasting.

Auxiliary sections are either external or connective.

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.This particular dichotomy was introduced by Jay Summach (2012). Example 1 below summarizes the hierarchical relationship between some of the most common section types. At the broadest level, musical sections are either core or auxiliary. Core sections are either main or contrasting, and auxiliary sections are either external or connective.

[](https://viva.pressbooks.pub/app/uploads/sites/12/2021/07/hierarchy_of_form_jarvis_02.png) Example 1. Core versus auxiliary formal sections.

Core Sections

The core sections identified in Example 1 typically 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

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.

Terminology

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:

primary theme (sonata)

refrain (rondo or verse-refrain)

exposition (sonata)

theme from a set of variations

chorus (verse-chorus)

dance chorus (verse-chorus)

strophe (AABA and strophic)

Contrasting Sections

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 connective auxiliary sections (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., becoming) can be used to create an accurate and unforced classification.

Stability

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 hypermeter, no modulation, diatonic melody, and diatonic harmony

Instability: relatively more change, increasing dynamic level, extreme registers, increased chromaticism (tonicization), increased rhythmic activity, modulation, sustained dominant, sequences (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.

Terminology

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:

Stable

secondary theme (sonata)

episode (rondo, fugue)

Note: episodes are just as often unstable

verse (verse-chorus)

Unstable

development (sonata)

episode (rondo, fugue)

digression (binary)

contrasting middle (binary)

bridge (multiple popular song forms)

Note: "bridge" in this context is referring only to popular-form terminology

Auxiliary Formal Sections

In addition to the core sections of