Odd time signatures are generally defined as ones where the number of beats per bar are not evenly divisible (e.g., 5/4, 7/8, 9/4, 11/4). Metric modulation happens when you imply an odd time signature (via accents or triplets) over a standard one such as 4/4. This concept has been used in African music and even by Bach, but it became popular in jazz through the influence of Miles Davis’ drummer Tony Williams. Groove displacement means moving an existing groove forward or backward a fraction of a beat. Let’s examine these three concepts.
1. Metric Modulation
In Ex. 1 we group quarter-note triplets into descending arpeggios of four notes per phrase. If we treat these groupings as new “measures,” we can fit three of these new modulated bars over the 4/4 time signature. The left-hand chords mark the beginning of each new modulated “bar,” while the bass line plugs along in the original time so you can keep track of where you are. This is the basic concept for most metric modulations. You can also group different note values (like dotted quarter-notes or eighth-note triplets) in this way.
2. 7/4 on Electric Pianos
Ex. 2 is a grouping exercise in 7/4 time. The left hand sets up a C minor ostinato while the right hand plays groups of five quarter-notes. Notice how the two groupings oppose one another. In the online audio clip, we have a Rhodes with a little delay on top and a Wurly on the bottom. If you’re having a hard time conceptualizing when the beginning of the pattern (pitch-wise) lines up with beat 1 of a measure, draw out the music so you can see where the different groupings come out together.
3. 9/4 on Organ
Ex. 3 takes an organ approach for time trickery. This one is in 9/4 and has an off-beat comping pattern in the right hand that goes to an on-beat pattern every other bar. For the bass part, pull the first and third drawbar on your Hammond or clonewheel all the way out. Add vibrato and Leslie however you like and avoid harmonic percussion.
4. Swing Time Tricks
The drummer is usually the band member who initiates these ideas, so it’s important to examine these concepts through a drummer’s eyes and ears. In the first two bars of Ex. 4, we have an ordinary swing beat with a quarter-note bass line. In bars 3 and 4, the drummer makes the quarter-note triplet the new pulse. The ride pattern from beat 2 in the original time moves to the second quarter-note triplet in the modulation. You can practice this away from the keyboard. Over any 4/4 pop music, tap quarter-note triplets on your lap with your right hand, mimicking a ride cymbal. With your left, accent every other triplet in the way the high hat would close on “two and four” in a traditional jazz beat. Slowly slip in the “dinga ding” on every second triplet with your right hand to complete the ride pattern.
5. Funky Groove Displacement
Ex. 5 is a funk application of groove displacement. A simple funk beat in bars 1 and 2 shifts an eighth-note ahead in bars 3 and 4. The funk bass line stays steady so we again know where we are relative to 4/4. This is another concept that you can practice away from the keyboard. I like to use my right hand for the hi-hat, left hand for the snare drum, and right foot on the ground for a bass drum. You can even sequence the bass line in this example for practice. Tower of Power drummer David Garibaldi is a master of this style. For a great example of groove displacement, listen to the bridge of the their tune “Squib Cakes” from the album Back to Oakland.