Section 5 – Form: D. Binary Form

While the previous pages dealt with phrase structures, this and the next few pages will deal with bigger structures. These large forms apply to entire movements or works.

The first type of large form we cover here is binary form. As the name implies, a work in binary form comprises two sections. Each section is usually surrounded by repeat signs (indicated by ||: and :|| below), though repeats are not required. Binary forms can be further categorized according to their thematic design and harmonic structure.

Thematic Design

The three categories related to thematic design are simple, rounded, and balanced. In a work in simple binary form, no substantial melodic material from the first section returns in the second section. The diagram below illustrates a prototypical simple binary form.

||:A:||:B:||

In a work in rounded binary form, the beginning or all of the melodic material from the first section returns at the end of the second section. A prime symbol is used if only part of the material returns or if the material is varied. The diagram below illustrates one possibility for a rounded binary form.

||:A:||:B A:||

The B part of the second section is called a digression. It usually presents fragmented and unstable material such as secondary chords, extended tonicizations, and sequences. They may also prolong dominant harmony. Digressions usually end in a half cadence called an interruption. This signals the return to the beginning material.

In a work in balanced binary form, the end of the melodic material from the first section returns at the end of the second section. The annotation (x) indicates the material that returns; it is placed after the uppercase letters to show that it occurs at the end of each section. Be aware that the material that returns may be transposed to fit a different key. (Comparing the solfège content may help!) The diagram below illustrates one possibility for a balanced binary form.

||:A(x):||:B(x):||

Balanced binary form differs from rounded binary form in that only the end of the first section returns in balanced binary form, whereas the beginning or all of the first section returns in rounded binary form.

Harmonic Structure

The two categories of binary form related to harmonic structure are sectional and continuous. In sectional binary, the first section ends in an IAC or PAC in the original key. In continuous binary, the first section ends with anything other than an IAC or PAC in the original key.

Combining Terms and Completing Diagrams

The complete label for a binary form should include one word related to thematic design, one word related to harmonic structure, and the word "binary." This means that there are six possible combinations: sectional simple binary, sectional rounded binary, continuous simple binary, continuous rounded binary, sectional balanced binary, and continuous balanced binary. A complete form diagram for a binary form must include repeat signs (if applicable); uppercase A, B, and/or A'; (x) (if applicable); measure numbers; and key labels. Below are three examples:

Sectional simple binary

  • The beginning of the first section does not return in the second section
  • The first section ends in an IAC or PAC in the original key
||: A :||: B :||
1 16  17 32
C:

Continuous rounded binary

  • The second section features a return to part of the opening material (hence A' instead of A)
  • The first section ends with a cadence in a new key
  • Measure numbers must be provided to show the beginning and end of each: A, B, and A'
||: A :||: B A' :||
1 16 17 24 25 32
C: G: C:

Continuous balanced binary

  • The end of the first section returns at the end of the second section
  • The first section ends with a cadence in a new key
||: A(x) :||: B(x) :||
1 8  9 16
C: G: C: