Rhythm modulation happens when a change in the meter or emphasis occurs where the old and new meters share a common pulse or subdivision. This is an effective concept because the transition often feels like the tempo suddenly shifted faster or slower. Are things really slowing down or speeding up? In this article, I want to discuss what happens in these metric transitions and the effect it has when the drum part modulates and the music itself does not change - creating rhythmic tension.

Understanding modulation means determing the common pulse or subdivision between the two meters. Let's begin with with 2 metric changes. In Example A accent every two 8th notes in 4/4 to accenting every three in 6/4 and in Example B accent every four 16th notes to accenting every three in 3/4. In both examples, the rate of the pulse/subdivision does not change as you transition to a new meter, only the emphasis. Of course whenever you place a consistent emphasis of threes we tend to hear triplets when they are not necessarily so, hence why we can use this illusion to deceive the listener [and perhaps fellow musicians who we feel are not paying attention!]

Now let's apply concept this to some basic grooves. In EX1a with the 8th note pulse staying the same, you transition from 4/4 to the new 6/4 meter and you change the BD/SD emphasis to every third 8th note and instead of 6/4, the listener will likely hear Ex 1b, a slower, "modulated" 12/8:?

In EX2a With the 16thth note pulse staying the same you transition from 4/4 to the new 3/4 meter but you change the emphasis to every third 16th note and in this case the listener likely will hear it as a faster, modulated 12/8 as shown in EX2b:

Let's take the rhythmic tension up a notch and spice up the space between the emphases in the modulated measures to really pull at your ears. Using the shuffle feel works wonderfully in this scenario. To achieve this in EX3a we subtract a hi-hat hit in the middle of every grouping of three 8th notes in the 6/4 and use a half-time feel with the back beat and EX4 shows how just by modifying the hi-hat part into a shuffle feel over an unchanging BD/SD from the 4/4 how tension can be created within the drum part itself. While this isn't modulating per se, it does in fact outline another aspect of creating rhythmic tension with the shuffle rhythm:

Also try these against a click or any cd tracks in 4/4. Remember the music will stay in 4/4 but you will not!

Now let's discuss some "real-world" applications citing the brilliance of drummers Gavin Harrison (Porcupine Tree) and Danny Carey (Tool). I want to reiterate that between any modulated meter transition, you want to find a common pulse or subdivision between them.

First, let's look at Gavin Harrison's work with Mick Karn on a tune called 'Plaster the Magic Tongue' from the Tooth Mother cd (1995). At the 5:23 mark you can hear Gavin go from 4/4 into a half-time shuffle in a modulated 12/8 feel [similar to EX3a but with a 16th note subdivision].

Second is an example of rhythmic tension coming from within the drum part is Danny Carey's work with Tool on the song 'Eulogy' from the cd Aenima (1996). At the 6:36 we see Danny expertly play some tricky hi-hat work in 3/16 over a repeated 4/4 groove which gives the impression of two meters happening simultaneously. It reminds me of when I've been on a train where I looked out the window to see another train alongside seeming to move backwards only to realize that I was the one moving forward!

I hope this has helped you understand modulation enough to start to working on your own exercises/ideas and find it a little easier to listen to bands like Tool, Porcupine Tree, Meshugga or King Crimson to name a few. Good luck!

John Kerr Drum Set Instructor: DiCenso's Drum Shop, Quincy, MA and White's Music, North Attleboro, MA Graduate SUNY Fredonia B.A. Music Business/Percussion Performance. John studied with Jeffrey Grubbs, Phil Ferraro, Louis Moreno and Dave DiCenso. He can be seen performing with a Boston Tool tribute act called Triad as well as with the Boston Philharmonic Orchestra and various Top-40 bands. John has had drum transcriptions published in Modern Drummer - most recently the chart for Led Zeppelin's 'Moby Dick' including John Bonham's solo! Look for more to come. His website is www.johnkerr.net