I’ve had a lot of confusing conversations about polyrhythms and polymeters because they’re so difficult to hear. Stumbling over the verbiage doesn’t help. Here’s a very simple explanation of each, and if you find yourself wishing for background info on rhyhtm and meter, click here.
Where are polyrhythms and polymeters found?
These are techniques that combine two simple rhythms or meters into a more complex one. They can be played in two separate voices, which is the easiest to recognize, but they can also be played in the same voice, like in separate hands on a piano, or even as part of one drum beat. They create a denser, more interesting texture and are sometimes very hard to recognize.
What is polyrhythm?
A polyrhythm is when beat divisions change within the measure, or don’t match up. A very common polyrhythm is called hemiola, when groups of three notes are played over (or instead of) groups of only two notes, or vice versa. Imagine counting to two over and over again, while your friend counts to three, but you always restart at one at the same time (your friend has to count a little faster than you). That’s hemiola. A good example of this is the Carol of the Bells. They can be divided in any other way, including divisions of 5/4, 7/6, etc.
What is polymeter?
Polymeter is when stresses on the beat don’t match up. Let’s say you and your friend were in the mood for shouting the number one, and you counted “ONE, two”, while your friend counted “ONE, two, three” counting at the same speed. You wouldn’t always end up on ONE together. Your shouting at different times would give the texture an interesting staggered effect. Polymeter is especially useful in band or orchestra music to emphasize different sections. (Polymeter is not the same as complex meter, which describes meters that don’t fit into the standard simple or compound categories, like 7/8.)
The difference (in one sentence):
Pieces of a polyrhythm take the same amount of time as each other, but the pieces of a polymeter are staggered. More abstractly, polyrhythms are more straightforward patterns, while polymeters are more about emphasis.