Journal · Music
Pattern Lamps, a polyrhythm game you can see and hear
Three rings of lamps each keep their own beat. Play them together and you hear a polyrhythm, like 3 against 4. Change how many lamps each ring has, then find out when the patterns line up again.
Pattern Lamps. Press Play to hear 3 against 4, and tap a lamp to switch it on or off. Nothing plays until you press Play, and sound is off until you turn it on.
What is a polyrhythm?
A polyrhythm is two or more rhythms played at the same time over the same stretch of time. In 3 against 4, one part plays 3 evenly spaced notes while another plays 4, and both start together. In Polyrhythm mode, every ring takes one lap in the same time, so that is exactly what you hear.
Polyrhythm or polymeter?
In a polymeter, every part moves at the same speed, one step per beat, but the patterns have different lengths. A pattern of 3 and a pattern of 4 drift apart, then line up again after 12 beats. Switch to Polymeter mode to hear it. The same number, 12, rules both modes.
How to count 3 against 4
Split each lap into 12 equal steps, because 12 is the smallest number that both 3 and 4 divide into. The 3 part plays on steps 1, 5 and 9. The 4 part plays on steps 1, 4, 7 and 10. Some drummers learn the sound with the phrase “pass the golden butter”, one syllable per note.
What this toy leaves out
- Every note lands exactly on time. Real players push and pull the beat a little, and that is a big part of how music feels.
- Each ring has 2 to 8 lamps. Real music uses other groupings too.
- The notes come from a five-note scale, so any pattern sounds calm. That is a design choice, not a rule of music.
Questions people ask
What is a polyrhythm?
Two or more different rhythms played at the same time over the same span, such as 3 evenly spaced notes against 4. The parts start together and end together.
What is the difference between a polyrhythm and a polymeter?
In a polyrhythm, different numbers of notes fit into the same span of time. In a polymeter, the notes all move at the same speed, but the patterns have different lengths, so they drift apart and line up again later.
What is the least common multiple of 3 and 4?
12. It is the smallest number that both 3 and 4 divide into. That is why 3 against 4 is counted on 12 steps, and why patterns of 3 and 4 beats line up every 12 beats.
What is the least common multiple of 3, 4 and 5?
60. Rings with 3, 4 and 5 lamps in Polymeter mode only line up again every 60 beats.
How do you count a polyrhythm?
Find the smallest number that every part divides into and split the bar into that many equal steps. Then mark the steps where each part plays. The counting grid on this page does this for you.