Polyrhythm and Polymeter

A polyrhythm combines two or more contrasting rhythmic divisions at the same time.

In 3 against 2, one layer divides a shared span into three equal parts while another divides it into two equal parts. Both begin and end together.

The tempo of the shared cycle stays fixed. Each layer places attacks at different fractions of that cycle.

Use six equal positions, the least common multiple of 3 and 2.

The three-note layer attacks every two positions:

X . X . X .

The two-note layer attacks every three positions:

X . . X . .

Combined, the attack order is both, three-layer, two-layer, three-layer before the cycle repeats.

Tap the three-note layer with your right hand and the two-note layer with your left.

Begin both hands together. The right hand taps on positions 1, 3 and 5; the left hand taps on positions 1 and 4.

Practice each hand while counting six even subdivisions. Combine them slowly and keep the spacing equal.

A spoken phrase can help, but the six-part grid lets you verify the timing exactly.

Cross-rhythm often refers to a rhythmic pattern that contradicts or cuts across the prevailing metric grouping.

The term overlaps with polyrhythm, especially for patterns such as 3 against 2. Usage differs across musical traditions and analyses.

Describe the actual layers and shared time span when precision matters.

Polymeter layers different metric groupings over a common pulse.

One instrument may repeat a three-beat pattern while another repeats a four-beat bar. Their beat speed is identical, but their cycle boundaries occur at different times.

If both start together, the three-beat and four-beat cycles align again after 12 beats.

Find the least common multiple of the cycle lengths.

For 3 and 4, the first shared multiple is 12. The three-beat pattern completes four cycles; the four-beat pattern completes three.

For 5 and 4, both return to their starting point after 20 shared beats.

This calculation tracks the repeating pattern. Musical accents or phrase changes may create additional landmarks.

Polyrhythm compares subdivisions of one shared span. Three notes and two notes fit inside the same cycle.

Polymeter compares repeating metric lengths over one shared beat. Bars or patterns start together and then fall out of alignment until the larger cycle closes.

Some music can support more than one analysis. State what counts as the beat, subdivision and bar before choosing the term.

No. A changing meter moves the whole ensemble from one meter to another, such as 4/4 followed by 3/4.

In polymeter, different layers maintain their own groupings simultaneously. A drummer may stay in 4 while a guitar riff repeats every 3 beats.

Notation may regroup the same sounding pattern in several ways, so listen for accents and cycle boundaries.

Many West African and Afro-diasporic traditions organize rhythm through interlocking timelines, beats and layered parts. Learn those patterns within their specific musical traditions and their own performance practices.

Afro-Cuban music, jazz and contemporary classical music use layered subdivisions. Progressive rock and metal often use repeating patterns whose lengths cross bar lines.

Electronic producers create similar cycles with sequencers, arpeggiators and delays set to different lengths.

Mute all but one layer and learn its accents against a steady pulse.

For 3 against 2, count six subdivisions and add the second layer only after both single patterns are reliable.

For 3 against 4 polymeter, mark every beat and say each pattern's first beat aloud. Continue through beat 12 without restarting early.

Record several cycles. A stable return point shows that the layers remained aligned.