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Structures & Forms

Air / Ballad Form

This is the most primitive structure. A simple melody is repeated with slight changes. These may be to accommodate different words (as in a strophic song) or merely decoration with melismata. Examples are found in folk-songs and carols.

The pattern is thus AA' or AA'A" etc.

Theme & Variations

This is a more advanced form of the same principle. The theme (which may have binary structure) is repeated with substantial changes. This may include decoration of the melody or harmony, change of key or time signature.

Binary Form

A structure having 2 sections. The first section ends in a new key. This is typically the dominant or relative major. The second section returns to the original key without using substantially new material. In many cases each section is repeated.

The pattern is thus AB or AABB.

Ternary Form

A structure having 3 sections. The first section may be repeated. The middle section is a contrasting episode. The last section is the same or similar to the first.

The pattern is thus ABA or AABA.

Rondo Form

A structure having a repeated subject separated by several contrasting episodes.

The pattern is thus ABACA or ABACADA etc.

Sonata Rondo Form

This is a modification of rondo form. It is often used for the last movement of a sonata or concerto - hence the name. One episode is reused as a second subject.

The pattern is thus ABACABA.

Ragtime Form

The rags of Scott Joplin seem to have their own form related to rondo form. There is a short introduction (I) and several repeated subjects (A, B, C & D). A link (L) or bridge passage may be taken from the first subject (A). There may be a coda modified from the introduction. Ignoring introduction and coda, this is rondo form with successively shorter uses of the main theme.

The pattern is thus IAABBACCLDDI.

Sonata Form (Compound Binary Form)

This is a complex structure often used for the first movement of a sonata, concerto or symphony. It may also be used for other movements. It has three main sections: exposition, development and recapitulation. The last section usually has a Coda but the others may have Codettas.

The exposition section introduces 2 subjects (melodies) linked by a bridge passage. These subjects are more substantial than those used in a fugue. The section may be terminated with a codetta and is usually repeated.

The development section explores the 2 subjects - different keys and variations. New material may be introduced - episodes.

The recapitulation section restates the original subjects. It usually ends with a coda.

Abridged Sonata Form

This is Sonata Form without the Development section. Instead there may be short section modulating to another key or a single chord (the dominant 7th).

Ritornello Form

This is the repeated use of a short passage to construct a movement, eg the first in a concerto. The repeats may be in various keys and be incomplete or ornamented.

Fugal Form

This is more a collection of contrapuntal techniques than a definite form. One or more short subjects can be made to interlock in various ways. However, some fugues have sections roughly equivalent to those of Sonata Form - exposition, development & recapitulation.

In the exposition, voices enter alternately with subject (tonic key) and answer (subject transposed to dominant key). This is a real answer if an exact copy, or a tonal answer if changed slightly to fit better. The countersubject is the continuation of the subject alongside the entry of the next voice. All voices must enter with either subject or answer. A redundant entry is a further entry of the first voice at the end of this section.

In the development section, the subject is used in other keys linked with modulatory episodes. Subject inversion, augmentation, diminution, stretto and pedal-point may also be used. A fugue that uses all possible techniques is a Ricercare. In the recapitulation section, the subject should reappear at least once in the original key.

In a double fugue, there are 2 subjects. These may be used together throughout or introduced separately and eventually combined.


A classical 18th century suite consisted largely of several dances from the following list. Most of the movements would be in Binary Form and the same key.

Pop Song Form

This is a structure or formula used in generating many popular songs. The introduction sets the mood and may include a memorable riff. It is largely instrumental, though there may be a recitative or other vocalisation from the singer(s). Then come a number of verses. Each of these, except sometimes the first, is followed by the refrain. There may be a bridge passage (with or without words) between verse and refrain. The refrain should contain the hook of the song and occasionally precedes the first verse. It is also frequently repeated without additional verses at the end of the song. Often there is a development section or contrasting episode near the end. This is typically instrumental like a cadenza, but vocal ones are not uncommon. There may be a coda, rather crudely called the "outro". Otherwise the refrain repeats until the performers decide to stop abruptly or by decrescendo ("fade" out).

The pattern is thus IVVBR[VBR]*DBR*C.

© Susan Foord ( 2010-06-24
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