Form in Music

In this installment of Music Theory Fridays, we’re going to talk about form.

Form in music is the overall structure of a piece. One of the biggest moments any young guitar player can have is realizing that “stuff repeats.” This simple idea that most high school and older guitarist realize right away is a major revelation to younger students. “Stuff repeats” is the big idea behind form in music too. Large sections can repeat or even little ideas. Good composition teachers will tell a student that if they come up with a cool idea, they should use it again. The same thing happens in rock music–have a cool riff? It’s now the chorus, and it comes back after every verse.

Form in music can be defined by a few things. I have a book that calls these things “Structural Phenomena” which is a fancy way of saying that something changes. This things that can change are just general musical ideas: Cadence, tonality or key area, tempo, meter or time signature, rhythm, dynamics, density (how many notes are in a given part), timbre or tone, register (how high or low a piece is on the staff), texture (block chords or arpeggiated? etc) and motive or melody.

So if something major changes, it’s probably a new section of the piece. The most important and obvious things are melody and cadences. If a piece sounds like it rests or concludes at a given point, that’s a cadence and it makes a great jumping point to start a new section.

Binary Forms

There are some typical forms that happen a lot in music. The first is binary, which is a simple two part form. That is, there’s two over all section. The simplest way to illustrate this is with letters (“||: :||”=repeat signs):

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

Or in prose: something (A) that is repeated twice, then something different (B) that’s repeated. Most times each section of a binary piece is repeated, but that doesn’t have to be the case. If a piece uses the same melodic material at the beginning of each section and delineates form by some other means. Most times we’ll label the form like this:

||: A :||: A’ :||

Something (A) then something that’s slightly different but uses the same ideas or material (A’=A prime}.

In addition to standard binary form, there’s something called rounded binary. The only difference is that the first section repeats after the second. The form looks like this:

||: A :||: B ” A’ :||

Some something (A), then something different (B) which cadences ( ” ), then a return of the original material that’s slightly different (A’). The return does not have to be a literal repeat of the first section, it can just take the first melodic idea and end it differently, which is often the case.

Ternary Form

There’s also Ternary, or three-part, form. Most times this looks like this:

A || B || A

The difference between ternary and rounded binary is that each section of ternary ends closed. That is, each section could stand on it’s own as a piece. The other big difference is that when A returns, it’s a literal repeat (notice there’s no ‘ after the second A, there’s nothing different).

How to Use Form for Interpretation

So let’s take a common piece and analyze it from a formal perspective. Sor’s Etude in B minor is a great example

We’d arrange the form like this:
A section, measures 1-16
B section, measures 17-32
A’ section, measure 33-end

Or in a visual format:

A ||: B ” A’ :||

OR!

A few things to notice that delineate the form. Measure 16 is the first time that that the constant eighth note pattern stops and we get a rest or quarter note. This is a huge change! The B section is indicated by a slight change in melody, but also by a change in tonality. You can hear the strange chords that start around measure 25 (after another quarter note! and cadence). You can hear this because it sounds as if the piece is “going” someplace away from where it was. What launches us back to the original key are is the dominant 7th chord found in measure 32, which has a strong tendency to go back to tonic. In this case that’s B minor, which is given in the next measure with a return to the original melody. From there, Sor transforms the first section to end differently and close the piece.

What this means for performance is that you can develop a hierarchy of rubato. Large sections should sound closed, you can do this as a performer (as Bream does in the recording) by slowing doing or playing with the time of the piece. Cadences at the end of smaller ideas like measure 24 or 8 should also slow down, but the energy of the piece has to be preserved. That means that tempo should be slowed more at the endings of larger sections and less at the end of smaller ideas.