Music: Practice & Theory Stack Exchange is a question and answer site for musicians, students, and enthusiasts. It only takes a minute to sign up.
Sign up to join this community
A very common (indeed ubiquitous) technique in electronic music involves the layering of loops of different lengths on top of each other.
Consider the following DnB track:
One can clearly distinguish a "fast" or "short" drum loop and a "slow" or "long" ambient loop.
Is there a technical term for this in music theory? I have done extensive research on the mathematical properties of musical rhythm (For example Euclidean rhythms and Christoffel words) but this is rarely, if ever addressed.
The layering of a 1 bar loop over a 2 bar loop over a 4 bar loop and so forth...
I don't think length of the loop matters. Consider following example: you take a 1 bar loop and you introduce a slight modification in every second repetition. Technically you get a 2 bar loop, but it doesn't differ much from the original 1 bar loop.
I think what you're asking about is voice independence. Various components of music differ due to their rhythm, the way the voices move, tone/timbre, articulation etc. They are not tightly locked to each other. These ideas are basis for polyphony and counterpoint.
One can contrast it e.g. with rhythm section of a rock band, where drums, bass and guitar parts are often arranged in a way they firmly support each other, and feel a bit like a single instrument.
In a general sense counter-rhythm or counterpoint would apply. Lots of people focus more on the pitch against pitch, the harmonic aspect, of counterpoint. But rhythm against rhythm is the other part. In counterpoint ratios like 1:1, 1:2, 1:4, etc. mean one note against one, one note against two, etc. Those are combined rhythms, or "layers" of rhythm.
Composite rhythm is another term to be aware of. That's the combined result of rhythms. So if one rhythm was eight notes and another was dotted eight plus sixteenth, the resulting composite rhythm is one eight plus two sixteenths...
Understanding composite rhythm can be very helpful for one person playing two rhythms at once like a pianist of drummer. Also, it helps when counting more complex polyrhythms.
...layering of loops of different lengths...
The thing that really matters is whether the different lengths conflict with a clear meter. When the beat is divided by 2 or 3 in basic meters like 4/4 or 6/8 the typically with reinforce the beat. That's normal so there isn't a lot of technical language to describe it. You normally just say "long" or "short", specific note values like "dotted eighth", etc. You can speak of the beat, subdivision, and multiple levels, but that's just the same as "beat", "shorter than the beat", and "longer than the beat".
If the different lengths don't fit neatly into simple divisions/multiples of the beat, you can bring in special terms like polyrhythm. Or, depending on how the different lengths are achieved you might talk about phase like is the music of Steve Reich.
In the clip you provided I didn't hear anything special rhythmically. It sounded like basic beat subdivision and very metrically regular. That isn't surprising for styles that are supposed to have a solid groove, or trance feel. You could probably find other EDM experimenting with odd layering, but it will likely have an more agitated feel.
Maybe mixing or re-mixing?
Probably the most important principle is that the length of each loop is either the shortest in the mix, or an even multiple of every shorter loop. As others mentioned, a common scheme is powers-of-2 (1, 2, 4, and maybe 8 bars), although other schemes are certainly possible. A layering scheme with loops of length 1,3,9,27 (powers-of-3) would be somewhat weird but definitely possible.
