Nested structures are quite simple to understand, but can add new levels of order and structure to your music.
If we start with two basic structures:
Binary: A B
Ternary: A B A
Nested structures refers to the idea that each of the structure “elements” (A, B, whatever) can actually be (or have) a whole structure in itself. This can be the basis for develping more complex structures from simple ones. For example:
We could choose ternary for our overall structure (ABA). But if we split it up further – replace A with the binary structure ab, and replace B with the ternary structure cdc, then we end up with the overall structure ab.cdc.ab. Read through this a few times if you didn’t quite get it.
Now think about taking that another layer deeper. You can keep nesting structures until you get down to individual phrases, gestures, motifs, even notes!
Also, consider that there are many more possibilities for “basic” (or primative) structures. As well as binary and ternary, there’s also rondo (ABACADA – commonly chorus,verse,chorus,verse,chorus,etc), sonata (A B <development> A B’)
Usually, there’s two ways to approach this: top-down and bottom=up. A top-down approach would be very similar to my example above – start with an overall structure, and then split it up into smaller and smaller pieces, stopping when you feel that you can easily populate a single piece. This is a “divide and conquer” approach.
A bottom-up approach would be the exact opposite – start with several very small pieces, then arrange them into larger and larger structures. This is very easy to do in a sequencer, where you can develop a few one or two bar sections, then copy and paste them in various orders and configurations.
Personally, I usually use a combination of the two. I build the piece bottom-up, but when I’m doing it I have a mental “plan” of how I want the entire piece to turn out.
By approaching composition in this way, you can create a piece with a very high level of coherence and order. Each section will fit exactly in its place, and repeated sections can give a certain unity – without having to resort to a simple verse-chorus-verse-chorus (or similar) structure. It’s also an easy way to add complexity by using relatively simple ideas.
Of course, the fun begins when you combine nested structures with techniques for subverting nested structures. Build your piece as usual, but add interest with variations, interruptions, twists and turns, bizzare trips to strange places. These kind of subversions are usually much more effective when you start with something with very high coherence and order.