Sections of variable length

Often I’ve found that using sections of “metric” lengths (four bars, eight bars, sixteen bars) can often give a piece a very rigid, predictable pace. No matter how exciting or interesting the actual musical material is, sections of metric length can really weigh a piece down.

This is because the listener knows (or can guess fairly accurately) when each change will occur. In her/his mind, the listener has heard a sigificant amount of the piece before it’s actually been played.

Let me give you an example. Let’s say that so far, every section has been sixteen bars long, and it’s very obvious whether each section is static or transitional. Within a few bars of hearing a particular section, the listener already knows what the rest of the section sounds like – sometimes to the point of not actually having to hear the remainder of the section. This is the point at which the listener becomes distracted, starting to talk, or getting bored.

A particularly effective way to reduce this effect is to use variable section lengths. Instead of making each section a “metric” length (four bars, eight bars, sixteen bars, etc), the idea is to make them “odd” lengths. This has two implications:

  • The listener will not be quite so sure how long each section will be. In fact, (if done well) sections will often end/change earlier than expected or later than expected. This can be taken advantage of to highten expectation and excitement.
  • The internal structure of each section will be more “fluid”: In sections of “metric” length, we tend to break them up into smaller bits of even length. For example, if we have a section of sixteen bars, we might very easily put in eight chord changes, one every two bars; or four chord changes, one every four bars. If we have a section with an “odd” length, it forces us to be more creative with the internal structure. For example, if we have a section that is thirteen bars long, we might split it into three groups of four bars, plus one; or four groups of three bars, plus one; or three groups of three bars, plus four bars… or anything else.

How you come up with the lengths is up to you. I composed a piece a several years ago where each section length was a Fibonacci number – the sections were all lengths like 5, 13, 21, 34, etc.

Another piece I composed had section lengths chosen by rolling dice.

Of course, it doesn’t have to be random. You might choose prime numbers, or the date of every Monday in the year, or anything else. You could even choose the lengths as you compose the piece, depending on the flux in the piece.

It’s really just about making the sections have lengths which aren’t even multiples of four or eight.

-Kim.

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