Classical music forms

In Lecture One of the Teaching Company's The Chamber Music of Mozart Robert Greenberg details the architecture of various musical works. The four forms he explains are: theme and variations (used in classical as well as jazz music, hence, the reason for the naming of the blog), minuet and trio form, rondo form, and sonata form.

Theme and variations form is the simplest. At the beginning of a movement, the theme is clearly stated. Each section thereafter in the movement is a variation on the theme. The variations may be as simple as a change in key or accompaniment, or a complicated restatement of the theme which may not be recognizable as the original theme. There may be any number of variations on the theme. The end of the movement will have a coda, an extended conclusion to the movement.

The minuet and trio form comes to us from the Baroque era dance. The minuet is a "stately, moderately paced three-step." (The same rhythm as a waltz.) The music form has an A-B-A structure, where the A is a minuet, B is a contrasting minuet, and the last A is a restatement of the original minuet. The contrasting B minuet was sometimes scored for only three instruments, hence it became known as the trio.

The rondo is a form in which the music in the movement returns periodically to the main, or rondo, theme. (In some ways, the minuet and trio is a rondo, in that the movement returns to the original theme at the end.) The rondo takes the form of A-B-A-C-A-coda, where A is the rondo theme, B and C are contrasting (but different) themes, and the coda ends the movement.

These three forms explained so far have in common that they are based on a single theme.

In the sonata form (sometimes refered to as sonata-allegro form), multiple main themes (at least two) are stated, varied, and then restated. The statement of the main themes occurs in what is called the exposition. Typically, the first theme is played in the home key of the movement. This is followed by a modulating bridge ("modulating" because it often is where a key change is made) before the statement of the second theme.

Following the the last main theme in sonata form is usually a cadence, part of the music that brings the exposition material to a close. Frequently, to help emphasize the main themes, the exposition will be repeated.

The development section will then play on the main themes in general ways; combining, varying, and so on. There may be multiple key changes, which makes the development a very active part of the movement.

The recapitulation in sonata form will bring back the main themes, usually with one change: where before the themes would be in contrasting keys, they will now be in the home key of the music. Finally, the movement will end with a coda.

These are general outlines of the forms, but many composers didn't stick strictly to them. Sometimes new themes were played in the development section or in cadential material. Sometimes themes from one movement are reintroduced in another movement. What is important is that there is a structure to classical music, and a listener can develop a greater appreciation for classical works when the structure is recognized.