What’s commonly called “implied metric modulation” refers to the auditory illusion that takes place when you apply patterns typically played in one subdivision (for example, 16th notes) within another subdivision (such as triplets). This makes the pattern sound like it’s being played at a different speed without affecting the actual tempo.
To illustrate the idea, here are two bars of quintuplets with an iconic rock groove forced into that framework. When you first try to play this pattern, make sure to count out loud and focus on how the superimposed beat feels against the quarter note.
Things get really fun with modulation when we use it as a tool to compress or expand rhythms without going as abstruse and awkward as in the rhythmic illusion in Example 1. If we mine the concept for little nuggets of rhythmic gold, and then bring the pattern back to 4/4, we can end up with some unique material.
For the first few exercises, we’ll keep a solid four-on-the-floor beat with the kick and snare, so we can focus on how various modulated rhythms interact with the pulse. First up is a funky 16th-based groove with a few bell accents on the ride. This is the basic pattern that we’re going to be expanding and contracting via modulation in subsequent examples.
To begin, we’ll expand, or slow down, into 8th-note triplets.
Now we’ll do the opposite by contracting, or speeding up, into 16th-note triplets.
Don’t try to hear the original ride pattern when working on Examples 3 and 4. Think of them as completely new syncopated triplet-based rhythms to add to your vocabulary.
In the next example, the same ride pattern is applied within quintuplets.
A good way to start incorporating these ideas into your playing is to pick a smaller section of the full pattern and loop it. In Example 6, I took my favorite sections of the quintuplet ride rhythm (beats 1, 2, and 3 of bar 2 and beat 4 of bar 1) and looped that.
Now rather than expand and contract a single sound source, let’s see what we can do with full beats. To keep these ideas from sounding like rhythmic illusions, start with something that’s a little more abstract. In Example 7, the only note that’s accented on the pulse is the kick on beat 1. In Example 8, that pattern is spread across 16th-note triplets.
Example 8 sounds strange when played completely on its own. But try to sink into the groove, and focus on internalizing how the kick and snare accents line up on different parts of the beat. When you’ve got the pattern flowing, grab your favorite pieces of the groove to create something more usable.
Example 9 is a variation that I came up with that starts from the final 16th-note triplet partial of beat 2 in bar 2 of Example 8. To make it sound more musical, I added a kick drum on beat 1 and turned the ghost note on beat 4 into an accent.
You can simplify the concept further by grabbing just the kick and snare accents from the original pattern and replacing the hi-hat or ride with something more common. Example 10 does this with a shuffle hi-hat pattern.
Aaron Edgar plays with the Canadian prog-metal band Third Ion and is a session drummer, clinician, and author. His latest book, Progressive Drumming Essentials, is available through Modern Drummer Publications.