Composing With Chance

Screen 1: Convert loops of differing lengths to real copies to extract the best parts.

If your beats are static, your melodies predictable, or if you’re just plain out of ideas, perhaps it’s time to introduce some random elements?

Aleatoric music is a composition technique incorporating some degree of ‘chance’. Some elements are left to the performer’s discretion, so there is a degree of random probability when and if some elements in the music will occur. Aleatoric techniques can be used to introduce variation and interest to an existing composition, to inspire new ideas or to create a wholly ‘generative’ piece of music. Modern DAWs and plug‑ins can introduce these deterministic elements into our music production. Here we’ll look at a few techniques available in most modern DAWs and many plug‑ins.

Loop‑De‑Loop

One simple way of introducing evolving interactions between parts is to loop regions (aka clips or events) of different lengths. Because of the offset timing, each iteration yields slightly different results when played back together. Too much indeterminacy, however, can lead to chaos. To get useful and interesting results, couple this with some regular recurring parts that anchor the music. For example, set up a regular recurring ostinato in one or more parts alongside the evolving loops.

This technique works great for film score‑style musical development. The permutations generated by the repeating loops, coupled with a steady pulse, create variety while maintaining thematic consistency.

The same idea works well with groove‑based music with either a static, or simple, harmonic progression. Set the loops to beat‑based offsets to create interesting syncopations. In the example in Screen 1 (above), I place a four‑bar (green) bass part alongside a (blue) clav part that is three bars and one beat long. When both are looped, the offsets generate some interesting (and some not so interesting) rhythmic interactions. To take control of the evolving parts, convert the loops to real copies, then choose the best bits.

Groove Is In The Part

Most modern DAW sequencers incorporate a parameter for probability, or chance, to determine the likelihood that a programmed note will sound on any given pass through the pattern. One way to use this musically is to reduce the probability of a steady part, like a 16th‑note hi‑hat, from occurring on every subdivision (Screen 2). The continual variations will undoubtedly yield interesting syncopated and funky patterns.

Screen 2: The varying probability amounts on each hi‑hat note generate continual rhythmic variations.

Another feature of modern step sequencers is the ability to set unique numbers of steps for each lane. Combining this feature with varying probability generates evolving rhythms using a much smaller set of steps. Varying the velocities leads to interesting ghosted and accented notes falling on different subdivisions.

In the example in Screen 3, I’ve taken a simple three‑step lane of hi‑hat notes with varying velocities and probability percentages. The result is a funky and evolving hi‑hat part.

Screen 3: A looping lane of three steps generates an evolving hi‑hat part containing accented and ghost notes.

Haunted...