Polyrhythm is the simultaneous combination of contrasting or conflicting rhythms. As guitarists we often encounter these patterns in contemporary composition. As a jazz guitarist, these rhythmic patterns can be used most effectively in soloing and comping, setting up complex rhythmic relationships within the band.
The examples below will give you a method to decode any polyrhythm which then can be played and internalized (with practice and patience) so that when this polyrhythm is encountered in composition or played in an improvisatory context it can be executed easily.
Download the pdf below and follow along.
1) Choose the two numbers you wish to superimpose.
2) Determine the least common multiple of the two numbers. In all of my examples it's the result of both numbers multiplied.
3) Write two lines of music (rhythm) using note values of equal duration (I prefer eighth notes for grouping purposes) one on top of the other with the number of notes in each line equaling the least common multiple. The top line will be for your right hand and the lower line for your left or, if played on guitar, the lower line is played with the thumb and the top line with the fingers.
4) Group the notes in accordance with the two numbers you are superimposing.
5) Place a number over each beat that is actually sounded counting each beat consecutively 1 - x.
6) Count evenly striking each sounding beat with either the right or left hand as indicated by your numbering.
7) Gradually increase the tempo until you hear the resultant rhythmic pattern (rhythmic pattern that results from the two lines combined).
Let's look at the simplest example: Two against three.
1) Our two numbers are 2 and 3.
2) The least common multiple is 6.
3) Write two lines of music with each line containing six eighth notes, one on top of the other.
4) Group the top line as two groups of three and the bottom line as three groups of two.
5) Numbering each note 1-6, place a number over each note that actually sounds.
6) Count to six striking each beat that is sounding as indicated by your numbering with the corresponding right or left hand. In this case the sounding beats are 1 (hands together) 3 (left hand) 4 (right hand) and 5 (left hand).
7) Gradually increase tempo until you clearly hear the resultant rhythmic pattern.
Once the rhythmic pattern is clearly heard either by tapping, or if you are a guitarist playing the pattern with the right hand fingering indicated, try playing through the little piece that follows each of the polyrhythmic examples. I reduced the notation in the pieces down to its simplest form except for the five over three example which could not be reduced.
I think you will have a blast playing these. It's mind-boggling when you try to listen to each rhythm separately as you play.
With this system it should be possible to figure out any possible polyrhythm. I have only shown the more common patterns. Try it for yourself and let me know if it works for you.