Binary and Ternary Form

Image By Louise MacPherson 18/12/2016

The form is the way the composer has arranged or structured a composition of music.

Binary form has two sections of music. Binary means two, which refers to these two sections. They are divided into A and B which are repeated. A is played, then repeated, then B is played, then repeated. It is structured A, A, B, B. The length of each section varies. Each section can be of equal length, however in many binary form pieces, B is longer than A. The music often changes key throughout section B which makes it more interesting. Sometimes there is a sequence, this is a phrase of music that has a similar idea to section A.

Ternary form is where the piece of music has A, B, A structure. A is called the statement, then section B is the contrast and is often written in a different key, this section is called an episode. Finally A played a second time is the repetition, where there might be a slight change from the first time it is played. However, it is still recognised as the same piece of music.

Bennett, R. (1980). Form and design. 1st ed. New York, NY: Cambridge University Press. pp. 10 to 13 and 18 to 21.