Polymeter vs Polyrhythm

Question

What is the difference between a polymeter and a polyrhythm? Do these words mean anything different for different instruments?

PS: I'm a drummer.

Answer 1

Hopefully these examples of 5/4:4/4 polymeter and 5:4 polyrhythm clears it up.

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Polymeter

Here is a simple example of 5/4 over 4/4 polymeter notated in 4/4 time. Notice how voice A's meter is five beats (the accents illustrates the starts), while voice B's meter is four beats, and they are sort of modulating over each other. After 20 beats their accented beats will coincide again. Important is that the beat tempo is the same for both voices!

Here is the same example but notated in 5/4 time:

You could also notate voices A and B each with a different time signatures (explicit polymeter notation), but it might look confusing if you're not used to it when the bar lines don't line up inbetween the staves.

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Polyrhythm

Here is a simple example of 5:4 polyrhythm notated in 4/4 time. Notice how both voices coincide and have emphasis on the first beat of each measure (or rather each complete beat ratio). Important is that the beat tempo is different between the two rhythms of voice A and B!

Here is the same example but notated in 5/4 time:

Answer 2

Polymeter: different voices/instruments that play different meters that de-synchronize themselves (a 9/8 piano part against a 4/4 drum part, or 7/8 on a 3/4.

Polyrhythms: different subdivisions that fit in the same bar. The classic Christmas tune "Carol of the bells" is an example of 2 against 3. Traditional Cuban rumba, and lots of West African drum rhythms use 6 against 4.

Source : Meters, polymeters, polyrhythms, compound meters. What are the differences?

Answer 3

Polyrhythms are multi-rhythms as in a bar of ,say, 8 quavers played against 12 quaver triplets (in the same bar).They don't necessarily fit properly,but they are playable.So, the bar length stays the same, but the divisions in it are varied simultaneously against another rhythm pattern in the same bar. Polymeters are changing lengths of bars in the same piece,e.g. 4/4 followed by 7/4 followed by 3/4, all the crotchets being equal in time to each other.An example would be 'Closest Thing to Crazy' by Katie Melua, or lots of stuff by Stravinsky.
Polymeters are also instruments used to measure differing values, e.g. temperature and voltage!!Not much use to drummers.

Answer 4

The first answer by Ulf is how I would use the terms also. I'll just point out that there are of course more complex ways of playing polymeters and polyrhythms than just using equally long beats for each of the two (or more) lines. In fact, polymeter and polyrhythm are not two different things, but two ends of a spectrum. For instance, if you take Ulf's example of a five against four polymeter but just play the first note of every group of five and of every group of four, you have a five against four polyrhythm.

If anyone's interested, here's an example of a polymetric piece in 12 against 47:

cheers from rainy Vienna, Scott

Answer 5

Polyrhythm and polymeter demonstrate the outer limits of written music. In truth if I play a seven note repeating phrase over a four note phrase at the same speed they will synchronise every 28 notes. I can notate this within one bar or I can fit one phrase in a bar and have the other run over the bar lines. It should sound the same either way. Music notation has not yet matured sufficiently to cover a full range of polyrhythms. Personally, as I am very interested in polyrhythm (I have named nearly 40 million of them) I tend not to use bar lines, and avoid using the word polymeter. I suppose if I was improvising in 7s over 4s (varying the 7 and 4 patterns) I might technically call it polymeter but I would expect to have to explain the word to most folks, most people I meet have some understanding of the word polyrhythm.

Answer 6

Note that they are only conceptually different. Any polymeter can be expressed as a polyrhythm and vice versa. To take the written example already provided, the top line is the polymeter and the bottom line is exactly the same thing written as a polyrhythm: