Tony Williams and Elvin Jones have been the first two drummers to explore the concepts of "implied time" and "metric
With these new rhythmic tools it became possible to give the audience the impression that the time meter changes completely and unexpectedly for a certain duration.
This device creates an unexpected tension in the music flow and then suddenly a sense of relief when the tempo goes back to the original meter.
Before these great two masters of our instrument the rhythm sections used other simpler ideas to change the time feel of a jazz song. For example to go in double- or half-time, while of course the progression of the chords remains at the same tempo rate.
The feeling in the metric modulation is that one of an irrational tempo changing... but in reality it is the opposite!
What is been used is the superimposition of a new pulse logically related to the original one.
In the first chapter of this article we analyse some polyrhythmical fills in 5/4.
In the second one we apply a metric modulation to the same odd time.
You can use a base 5/4 swing pattern that you like. Here just as example:
A polyrhythmical fill: 3 against 5
Now, if we divide the pulse in triplets, we obtain 3x5=15 notes in each bar.
3 is our pulse, so let's try to consider the eighth triplets in groups of 5 notes, with the following pattern:
This is the result:
I suggest to practice this polyrhythmic figure with the metronome on the quarter notes or to keep the pulse with the foot.
When it flows, you can practice alternating three bars of swing and a bar of this fill, then two-two and at the end four-four.
Next we can orchestrate this idea by moving the accents around the drumset.
At first we can play a one-bar-phrasing:
On the E note in violin key there's the first tom, on the A the floor tom.
The next step is to organise the 5-notes-pattern not in groups of 3 (5x3), but in something other, to release the fill from the form of the bar.
Let's take for example a group of 4 (5x4) with the accents playing the form Snare-Tom-Snare-Floor Tom.
The cycle lasts 4 bars, as 12 is the least common multiple of 3 and 4.
Let's practice this 4-bars-fill alternating with 4 bars of the base swing pattern.
When we master this polyrhythmic idea of 3 against 5, we can apply it to more interesting phrasing.
Let's take for example the following one:
Then let's apply it on a 5/4 bar:
We can proceed the same way as for the former 5-notes-group.
Also, let's orchestrate it in 1-bar phrasing:
And then in a 4x3 group of 4 bars:
A metric modulation: from the quarter to the dotted quarter
In the first chapter of this article we considered the pulsation as divided in triplets.
Let's take now the eighth notes (without swing).
We play the eighth notes on the Snare and we group them in group of three by adding the Bass Drum as written:
Now the resulting metric modulation is from the quarter note:
to the superimposed dotted quarter note:
Now comes the funny part...
Let's apply a shuffle groove to the new pulsation:
At first we can counterpose 2 bars of the base 5/4 swing pattern and 2 bars of the new implied time.
At the end we can extend the implied shuffle for a whole cycle, that lasts 3 bars, as 30 is the least common multiple of 6 (the eighth notes of the shuffle cell "Bass-Snare") and 10 (the eighth notes of the 5/4 bar):
Or let's try to play a swing on the ride cymbal:
Therefore this is the implied time:
If you are new with this rhythmic ideas, I suggest to look at the masterpiece of John Riley "Beyond Bop Drumming", published by Alfred Music.
You can find there a great explanation and introduction to the implied times and metric modulations, starting from a more common 4/4.
Hope you find it interesting!
Thanks to Florian Speth and his Single Coil Studio for the audio recording.