Fig. 2.

One measure of structure-preserving and structure-violating variations on isochronous and nonisochronous excerpts. A single extra note (in gray) is inserted into each measure for both types of variations. In structure-preserving variations, the note preceding the change is shortened to maintain the meter and the duration of intervals in the drum pattern. In structure-violating variations, no existing note durations are modified, resulting in an increased long interval in the drum pattern and an extra count.