Put simply, variation is when you take a bit of music (it could be one bar, one instrument, or even a whole section) and you change it. More accurately, you would probably make a copy of that bit of music, and change the copy. The key is that the changed copy still bears some resemblance to the original (ie, we’re not talking about transforming it into something unrecognisable).
What then, is development? Development is a more sophisticated version of variation. If we define variation as “making some change”, we could define development as “using a defined process to make a variation”. At first glance, the difference may look like one of semantics, but I assure you it’s more than that. Before we discuss why we’d want to use development, I’ll give you some examples so you know what I’m talking about.
Let’s say we have a drum pattern. Let’s say we want to vary the position snare drum. If we were to make a variation, we might “randomly” move the snare drum hits around, perhaps inserting some or removing some. The variation will not actually be “random” – we’d be changing the snare hits according to what we think sounds good. I use the term “random” because it helps illustrate the difference between variation and development.
If we were to make a development of the drum pattern, we would use a defined process to alter the snare drum hits. Defined process? Well, we could do something like move all the hits one sixteenth of a bar earlier. Or we might gradually increase the density of snare drum hits (one hit in the first beat, two hits in the second beat, … , four hits in the fourth beat). Or we might make the velocity (volume) of each snare drum hit increase as they progress throughout the bar. Or we might do all three.
Let’s say we have some melody, and make a copy and we want to change the notes on the copy. If we were to make a variation, we’d change the notes “randomly” – according to whatever we think sounds good.
If we were to make a development, we might do something like transpose each note one step higher than we transposed the previous note. Or we might change all upwards jumps to equal downwards jumps (and vice-versa). (You might want to measure “steps” in your favourite scale, to avoid getting “wrong” notes. Or you might like the sound of the “wrong” notes!)
The difference between variation and development, is that for development we’re using a defined process over a period of time. You may also choose to think of it as a repeatable process. We could take the process that we used, and apply it to some other tracks, or another section.
From those examples, you might already be thinking about some ways in which development may be useful as an alternative to variation.
One advantage (that I’ve already mentioned) of development over variation is that you can use some process, and then apply the same (or a similar) process to other bits of music. For example, you could perform some development on a drum track during a bridge section, and then do the same thing on the bassline, or the chords, or whatever. Or you might make a development of the main melody, then perform and inverse or opposite development on the bassline.
Of course, multiple develpment doesn’t have to be just in parallel – you could do them one after the other. For example, you might have a really dense drum pattern. You might have it plain once, then for the next repeat you could use some process to remove some hits. Then for the next repeat perform the same (or similar) process on the previous development, and keep doing that until the drum pattern is empty.
Another interesting approach could be to apply a similar process across different lengths of time. For example, you could come up with a process to let you thin out a drum pattern rapidly – so that at the start of the bar it is complete, but by the end of the bar there is nothing left. You could then apply a similar process to the bassline, but across two bars. Then do the same thing to the pad, but across four bars. Then the meldoy, across eight bars…. or something like that.
While I’m using typical tradtitional western music constructs (notes, metric rhythm, drums, melody, chorus, etc) for examples, that these principals are appropriate to almost all kinds of music.