Changing Speeds

This example might not find its way into the final version of the TAM app but will be used during life performances. The main bass groove is transformed by two metric modulations, the first one uses the triplet (bar 6) as the new reference speed and the second one the quintuplet (bar 11). Pianist and composer Vijay Iyer used this rhythmic transformations on his adaptations of Mystic Brew and Human Nature (cf. my original post here peckels.com/blog/mystic).

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The Limits of Adaptive Music

These rhythmical transformations are the hallmark of South Indian Music. There are different ways to indicate these rhythmical devices in Western Music notation. I chose to use the metric modulation indication with new tempo markings. A tuplet notation with group bracketing1 would also be possible.

Transforming this example in fmod to an adaptive, randomized example reveals the limits of using audio game engines as well as most DAWs for writing complex rhythmical music with an added layer of structure options. Rhythm changes are easy to manage in Pro Tools, Logic, etc. but this is not the case with tuple writing. While logic has built-in functions up to quintuplets only Cubase handles everything above gracefully. On iOS over the last year some interesting non-linear DAW’s have been designed with different plugins e.g. Victor Profs Atom Piano Roll 2 that offers a piano roll like editor with divisions up to 13 and that can be combined with AUM an audio mixer, plugin host and recorder.

There are two problems that occur when trying to develop these rhythmical transformations in one of the randomized versions of The Souvenir Shop tune. First the metrical grid is extended from 8 to 13 to 21 eight notes so all the other instruments would need to be re-recorded to make them fit, and different adjustments would be necessary to give a convincing rendering of the tune.

The second difficulty lies in the expanding number of combination possibilities with only these three different metric grids:

  • every four bars (1, 9 and 11) a version could repeat itself
  • every version could go to one of the two other versions (a total of six possible combinations)
  • each time the right metric modulation would have to be played (one could imagine ignoring this transition and doing a “hard cut” transition).
  • (N.B. but key: real musicians have none of those limitations, given enough practice)

By leaving out the tuple metric modulations the randomized version is easier to integrate with fmod. The metric changes now happen randomly with the bass not anticipating the new tempo by playing a triplet, quintuplet or a tuplet but only a sustained note:






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Because of the use of these additive and subtractive rhythmic devices the transitions are still interesting and don’t sound like simple tempo changes.

In generative music those rhythmic transformations with added random elements are promising, and I will now take a detour into more Karnatic techniques and link them to live coding and modular synthesis where random features and capabilities are widespread.


  1. Reina, R. (2017). Applying Karnatic Rhythmical Techniques to Western Music. Routledge, (p45). ↩︎