MUS 312 Form & Analysis

D. Binary Principle

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Binary principle is embodied at a low structural level in the two-phrase period:  the antecedent/consequent idea.

Pieces of music which are divided into two main parts--the second of which is perceived as an outgrowth of the first--exemplify the principle.  The two main sections are referred to as Part A & Part B (duh).

The binary principle is expressed above all else in terms of tonal movement.

Part A:  typically involves motion from the tonic to an authentic cadence in a related key (sometimes to a half cadence in the original key).

Part B:  serves as a return, and re-establishes the tonic before the final cadence.

The interdependence of the two parts rests primarily on motivic relationships.

The binary principle embodies:

1. two major sections, which may or may not be subdivided into smaller ones, and

2. the process of movement away from, and back to, the tonic.

Simple Binary Form

  1. Simple binary form involves the unfolding of a single musical idea in two main parts.  The parts are separated by a double bar with repeat signs.  Usually, each part is either a single, indivisible section, or a phrase group.  Periodic structure is rare, but sometimes appears in the A section.

  1. Part A:  often expository and transitional in function, sometimes developmental.

    Part B:  longer and less tonally stable than Part A; often developmental right after the double bar, followed by a closing section of expository or terminative function in the tonic.

  1. In simple binary form, the melodic/thematic material that was originally stated in the tonic in Part A is not literally restated in Part B.
Part A Part B
I - - - - - - - - - - - - - - - -V V - - - - - - - - - - - - - - -  I
i - - - - - - - - - - - - - - - III III - - - - - - - - - - - - - - -  i
i - - - - - - - - - -  - - - - - -v V - - - - - - - - - - - - - - -  i
Phrase Group Phrase Group
Single Section Single Section
Period  
Expository-Transitional Developmental-Expository
(Developmental) (Terminative)

Rounded Binary Form

  1. In Rounded Binary, the original melodic/thematic material returns in Part B in the tonic key.  "Rounded" refers to the rounding out of the structure as a result of such a return.
Part A Part B  
I - - - - - - - - - - - -  V V - - - - - - - - - - -  V I - - - - - - - - - - - - - I
i - - - - - - - - - - - - III III - - - - - - - - - - -  V i - - - - - - - - - - - - - i
i - - - - - - - - - - - - - v V - - - - - - - - - - -  V i - - - - - - - - - - - - - i
Theme   Theme
Period Phrase Group Period
Expository--- Developmental--- Expository
---Transitional (Transitional) (Terminative)

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