Like for any other part, adding variation to the kick drum pattern adds interest and scope. Generally speaking, there are two kinds of variation – changing the timing of notes (keeping the same density) and adding/removing notes (changing the density). These variations are most effective when a regular pattern has been established (repeating for several bars) before presenting the variation bar. This frames the variation pattern in the context of the regular pattern. This effect does not last long though – if the variation bar is repeated several times, it becomes the new regular pattern. The effect of any change (such as excitement or anticipation) fades.
Pulling Notes Forward
This is changing the timing of a kick drum note so it plays earlier than expected. For example, if the regular kick drum pattern is “First and Third” (kick drum plays on the first and third beats of the bar), a variation might be to pull the second kick forward from the third beat to halfway between the second and thid beats. This will add a sense of excitement for the listener, as they hear the kick drum play earlier than expected.
Pushing Notes Back
The opposite of pulling notes forward is to push them back. This is where kick drum notes are played later than expected. Using the same example (“First and Third”), a variation might be to push the second kick back from the third beat to halfway between the third and fourth beats. This will add a sense of heightened expectation and anticipation for the listener because the kick drum doesn’t sound when expected, but the effect is tempered by eventually providing the kick a little later.
Adding notes as a variation is a more effective case of pulling notes forward. The added kicks are heard as occurring earlier than expected, but the “original” kick is also heard. The added kick also increases the density of the pattern, which also adds excitement.
Missing notes is an extreme case of pushing notes back. Instead of simply changing the timing of a kick so it is heard later than expected, the kick is removed altogether. This results in a sense of anticipation that isn’t fully resolved – it is only partially resolved when the next kick hits.