What are Polyrhythms?
A polyrhythm combines contrasting rhythmic divisions at the same time, such as three evenly spaced notes against two over one shared span. The layers can share the same meter; their different subdivisions create the contrast.
Polyrhythms are everywhere and many musicians use polyrhythms in their compositions without even understanding them. To get a better grasp of this simple but hard-to-explain musical concept, the best way is to get back to its definition and break it down into parts.
Contents
Hear Three Against Two
Use this online tool to hear both layers together, then solo either part to follow its spacing.
Understanding polyrhythms
Playing concurrently means the rhythmic layers sound at the same time. In this introductory 3:2 example, both layers begin together and return to that shared starting point after one complete cycle.
Different sounds do not automatically create a polyrhythm. In a 4/4 time signature, a kick on every quarter-note beat and a clap on beats 2 and 4 share ordinary subdivisions. Three evenly spaced hits over those same four beats would add a contrasting three-against-four division.
For that three-against-four pattern, place the three hits at the start of the bar, one-third of the way through it and two-thirds of the way through it. Keep the four quarter-note beats unchanged. The distinction comes from spacing, not from the instrument sound.
A tuplet divides a rhythmic span into a different number of equal notes from its usual subdivision. For example, three triplet eighth notes occupy the time normally taken by two eighth notes. Tuplets can occur within a beat or another span; they do not have to divide an entire measure.
To feel a 3:2 division, keep the two-note pulse steady while placing three equal notes across the same total duration. Counting three does not change the tempo of the underlying pulse. Other ratios work the same way over their specified span.
Count the underlying pulse and the tuplet subdivision separately, then listen for their alignment. In the example below, the two- and three-note layers meet at the cycle start. Not every tuplet has to start on beat 1.
Examples of polyrhythms
The clearest starting point is a short controlled example with just two rhythmic lines. Once you can follow each separately, combine them and listen for where their notes coincide. For longer listening, compare the rhythmic organisation in the Dave Brubeck Quartet’s “Take Five” and Led Zeppelin’s “Kashmir”. Distinguish the bar’s meter from the subdivisions or phrase lengths of the individual parts; an unusual meter alone does not establish a polyrhythm.
The Youtuber “robertinventor” uploaded a series of simple (and more complex) polyrhythms into his channel using intuitive graphic visualization. These should help you not only to get familiar with the concept of polyrhythms but also train your sense of rhythm.
This is a 4:3 polyrhythm, like the one mentioned in our hypothetical techno track. The 4 stands for a classic 4/4 division, while the 3 stands for a triplet. Notice how both rhythms always line up perfectly on the 1 (i.e., the beginning of the measure).
A 5:3 polyrhythm takes things further by combining a quintuplet and a triplet. Keep in mind that, while this is a 5:3 polyrhythm, these two sounds can be used in a 4/4 song. A 5:3 polyrhythm doesn’t necessarily involve a 5/4 time signature.
Here, “robertinventor” takes things further by demonstrating various polyrhythms in one single video. The 8:9 polyrhythm is particularly dizzying.
To truly interiorize the concept of polyrhythms, it’s important to understand what makes them different from other rhythm-related musical concepts such as polymeter, syncopation, and hemiola.
Polyrhythms vs polymeters: what’s the difference?
Many people misunderstand polyrhythms with polymeters. Unlike a polyrhythm, a polymeter involves the use of two or more rhythms playing simultaneously in different-sized measures.
So, while the sounds of a polyrhythm always “reunite” at the beginning of a measure, the sounds in a polymeter don’t need to do so (and usually won’t). If polyrhythms are made of different tuplets clashing against one another, polymeters are made of loops with different time signatures clashing against one another.
Let’s get back to our hypothetical techno track. It’s playing at a 4/4 time signature with the kick drum on the 1, 2, 3, and 4 and the clap on the 2 and 4. For the track to feature a polymeter, one would need to add a hi-hat loop playing not a triplet, but at a 3/4 time signature.
This means that the hat would align perfectly with the subdivisions already contained in the song, but that the start of the 3/4 measure would not match the start of the 4/4 measure.
Polyrhythms vs syncopation: what’s the difference?
Polyrhythms and syncopation are two completely different concepts even though polyrhythms involve syncopation. Syncopation refers merely to rhythms that rely on subdivisions other than the fundamental subdivisions contained in a measure.
Examples of syncopation can be extremely complex, but something as simple as playing off the beat (i.e., in the beats 1-and-2-and-3-and-4-and) is already considered an example of syncopation.
In other words, syncopation is about adding notes to subdivisions other than the fundamental subdivisions of the time signature, even if these are divisible by the time signature. In a 4/4 song, a 16th-note hi-hat pattern already constitutes syncopation.
Polyrhythms vs hemiola
In music theory, hemiola refers to the 3:2 ratio in both pitch and rhythm. The 3:2 relating to how pitch works is a perfect fifth. The 3:2 ratio relating to how rhythm works is a specific type of polyrhythm.
To put it simply, hemiola is the name given to the 3:2 ratio that, when applied to rhythms, results in a 3:2 polyrhythm. A 3:2 polyrhythm is made of a triplet playing over a duplet. A hemiola is merely the conceptual name applied to the ratio of such a polyrhythm in the realm of music theory.
Conclusion
What drives many people away from music theory is the fact that many musical concepts are harder to describe than they should. The concept of polyrhythms surely fits the part: you’ve heard it everywhere and you may even apply it in your playing and songwriting, but can you explain it in simple terms to someone else?
Hopefully, this short guide on what “polyrhythm” means will be useful for anyone trying to grasp an idea that’s harder to put into words than it is to understand.
