- Ternary forms have an ABA formal structure.
- A may immediately repeat and B may immediately repeat, but A and B do not repeat together, and neither do B and A.
- Repeat signs are common but not required.
- The B section typically contains contrasting material a new key, and it may be relatively unstable.
- Auxiliary section are possible before, between, and after each section.
Ternary form is a musical form consisting of three distinct sections with an ABA pattern of large-scale repetition: an opening section (A), a contrasting section in the middle (B), and then a return to the material from the opening section (A). (Though it might seem logical to call ABC ternary form as well, it is more often considered because each section contains different music.)
As shown in, each section in ternary form may immediately repeat, either with repeat signs (most commonly) or written out. However, A and B do not repeat together, and neither do B and A.
|𝄆 A 𝄇||𝄆 B 𝄇||𝄆 A′ 𝄇|
While the contents of each section can vary greatly concerning phrase and form, each section commonly comprises multiple phrases, and very often those phrases combine together into a complete form (very often a binary form). A ternary form is considered to be (or composite) if one or more of its sections comprises a complete musical form. If a section does not contain a complete form, it can be called . In many compound ternary forms (like minuet & trio or scherzo & trio in particular), all sections contain complete forms (often rounded binary form). In compound ternary forms of the 19th century, however, the last A section is often shortened and is simple, not compound.
|𝄆 A 𝄇||𝄆 B 𝄇||𝄆 A′ 𝄇|
|𝄆||A 𝄇||𝄆 BA′||𝄇||𝄆||A 𝄇||𝄆 B||𝄇||𝄆||𝄆 A 𝄇||𝄆 BA′||𝄇|
|𝄆||A||𝄇||𝄆 B 𝄇||𝄆 A′ 𝄇|
|𝄆||A 𝄇||𝄆 BA′||𝄇|
Diagram of a ternary form where only the first section of the form comprises its own complete form. See Chopin’s Mazurka in A minor, Op. 17, no. 4 for an example of this.
The second section of a ternary form, usually referred to as the B section, is expected to provide contrast with the A section that preceded it. This contrast may come from a variety of musical domains including key, mode, texture, time signature, rhythmic ideas, melodic ideas, range, instrumentation, register, and so on. The length of B, however, is expected to be generally proportional to that of A.
In some genres (like the minuet & trio), the A and B sections exhibit a relatively similar level of stability, usually because they start and end in the same key and contain phrases that are . In other genres (arias in particular), the B section is often less stable than A. B‘s instability is largely due to starting and ending in different keys and having a generally phrase-structural organization than A.
Closed and Open Harmonic Endings
As with other forms, each section can be described in terms of being harmonically or .
Modulation within a Section
Modulation is possible within each section in ternary form, but it is very rare in the A section and should be considered atypical when found there. Modulation in the B section is much more likely to be found in an aria than in dance forms like the minuet and trio.
Like other forms, ternary form can contain auxiliary sections. Small transitions, small retransitions, small prefixes, and small and large suffixes are common. See the chapter on Formal Sections in General for more information on auxiliary sections.
- Bernhard Crusell – Clarinet Quartet, Op. 7, III, Menuetto (.pdf, .docx). Access score and audio.
- Josephine Lang – Traumbild, Op. 28, no. 1 (.pdf, .docx). Access score and audio.
An attribute of a musical form where no sections of music return. For example, a form with sections A B C. Similar motivic material may be present in different sections, but the sections would each be considered distinct. A piece that doesn't have any clear sections and seems like a continuous churning of musical ideas can also be described as through composed.
A type of ternary form where at least one of the form's parts (A, B, or the second A section) is comprised of its own complete form (typically a binary form). The term "compound" can also be used to clarify that a single section contains a complete form. Compare with simple ternary form.
A ternary form whose sections are each made up of one or more phrases but not complete forms. The term "simple" can also be used to clarify that a single section does not contain a complete form. Compare with compound ternary form.
This is William Caplin's terms that he defines as, "A formal organization characterized by conventional theme types, harmonic-tonal stability, a symmetrical grouping structure, form-functional efficiency, and unity of melodic-motivic material (compare loose)." (Quoted from Caplin's 2011 book, Analyzing Classical Form, p. 714)
This is William Caplin's terms that he defines as, "A formal organization characterized by nonconventional thematic structures, harmonic-tonal instability (modulation, chromaticism), an asymmetrical grouping structure, phrase-structural extension and expansion, form-functional redundancy, and a diversity of melodic-motivic material (compare tight-knit)." (Quoted from Caplin's 2011 book, Analyzing Classical Form, p. 709)
A phrase or module is harmonically open when it ends on a harmony other than tonic.
A phrase or module is harmonically closed when it ends with tonic harmony (I in root position).