The Musician’s Guide to Binary Form in Music

What is binary form?

Binary form is a type of musical form usually found in classical music, and Baroque pieces in particular.

In this post, we’re going to take a look at binary form and how it works. Then, we’ll go over a few examples in music, so you can hear it in action.

But before we learn about binary form, let’s talk about musical form. What is musical form? And how does it work?

What is Form in Music?

Musical form is a way a song is structured and organized. A song’s form is determined by several different factors, like its melody, harmonies, and rhythm.

Like how some poems are haiku’s, rhyming poems, or limericks, songs are categorized by form.

The main way to find a song’s form is to divide it into pieces, then label those pieces (A, B, C, D, etc), and notice how often certain pieces are repeated.

Labeling the Music

There are four main ways to split up the music:

1. Measures (bars)
2. Phrases
3. Passages
4. Movements

An individual bar may be used in very short songs, but most of the time, we divide songs into phrases or passages.

A phrase is usually less than five bars long. It’s like the equivalent of a sentence. Phrases have a clear beginning and end. If you’re having trouble finding the phrases, just look for a rest. Many phrases end with a rest or a place to breathe.

Passages are chunks of several different phrases. Think of a passage like a page in a book. It contains anywhere from 4 to 16 phrases. This might be a verse in the song, or it could be the main chorus.

And a movement is something you won’t see too often in today’s music. Symphonies usually have four movements. Movements are self-contained. You might think of movements like books in a series. Each of the Harry Potter books could be read on its own, but when you put them all together, they form a cohesive storyline.

So let’s say you divide your song up into passages, by chorus and verse. A song like “Amazing Grace” only has verses, so it would be labeled AAAA. However, a song like “Dust in the Wind” by Kansas has a different form, because it contains both verses and a repeating chorus. We label “Dust in the Wind” as ABABA, or rondo form.

There are several different types of musical form. If you want to learn more about form in music, make sure to check out our post on form HERE.

Now that we know what form in music is, let’s take a look at one specific type of form– binary form.

What is Binary Form?

Binary form is when a piece of music has two distinct parts that repeat throughout the song.

We label this as AB, or AABB. The two sections (A and B) are about the same length, and they may have similar harmonies.

Also, the A section sometimes repeats before the B section plays, so you might see a pattern that looks like AAB. AAB still counts as binary form.

A great example of binary form in music is the folk song, “Greensleeves.”

In this video performance of “Greensleeves,” you can hear the first sections (AA) from :08 to :31. Then starting at :32, notice the chorus, which also repeats until :52.

This gives “Greensleeves” a form of AABB, which is binary form.

Rules of Binary Form

In the Baroque period, when the binary form was first popularized, there were some rules surrounding the sections of binary form.

The A section started in one key, then modulated (changed keys) to a different key.

In a major key, this new key change would be the V of the original key (based around the fifth scale degree). If the song was minor, the key would change to the III of the original key (based on the third scale degree).

The B section started in the new key. Then after a while, it modulated back to the original key, and the song would end.

Nowadays, we don’t see this in music too much any more. But there are some subcategories of binary form that you should know about, like simple or rounded, sectional or continuous, and symmetrical or asymmetrical.

Simple or Rounded Binary Form?

As you might guess, there are multiple different types of binary form. Two of these subcategories include simple and rounded binary.

Simple Binary

“Greensleeves” is a good example of simple binary in music, which you can listen to in the video above.

Simple binary happens when the B section does not repeat part of the A section after it. The A section and B section are separate, and they do not combine at any point.

You can also hear this in Bach’s “French Suite No.2 in C Minor,” during the “Allemande” movement. In this piece, the A section plays, then the B section. The B section does not end with a segment of the A section.

Rounded Binary

In rounded binary form, the B section ends with a small piece from the A section.

Some people write rounded binary as ABA¹ but you probably don’t need to write it that way, since it’s too easy to confuse with Ternary form.

As long as the A and B sections are distinct, and only a small bit of the A section is repeated at the end, it still counts as binary.

One example of rounded binary is the folk song, “Oh Susanna.” In this video performance, you can hear how the verse (A) and chorus (B) are separate, but the chorus ends with a tag from the verse.

The third movement from Mozart’s “Piano Sonata in D Major” is another example of rounded binary. Notice how the two repeated sections in the first page act as a rounded AABB.

Sectional vs. Continuous Binary Form

Another way to divide binary form into different subsections is sectional or continuous binary form.

A song is sectional binary if the A section ends with a perfect cadence. (A perfect cadence means it ends on the tonic chord, which is doh, mi, and so. In C major, that would be C, E, G, and in G major, that’s G, B, and D.)

If the A section ends with any other kind of cadence, such as a dominant chord, then it is continuous binary.

In our examples above, “Oh! Susanna” is sectional, because it ends on a perfect cadence. However, Mozart’s “Piano Sonata in D Major” does not end on a perfect cadence, so it is an example of continuous binary.

Symmetrical vs. Asymmetrical

And last but not least, the third way to divide binary forms is by dividing symmetrical and asymmetrical.

It’s pretty easy to tell if a piece is symmetrical or asymmetrical.

If the A and B sections are roughly the same length, the piece is symmetrical. If they’re different lengths (for example, the A section is much longer than the B section), the piece is in asymmetrical binary.

Summary

Binary form used to be very popular during the Baroque period, but now it’s a little less common.

You can tell if a song is in binary form because it has two sections played back to back, which is written as AB or AABB.

Once you know that a song is in binary form, you can figure out what subcategories it fits in, such as simple vs. rounded binary.

Thanks for reading! We hope this post helps you learn about different types of binary form in music. If you have any questions, let us know in the comments!