advanced · LCM = 20
Four against five — a broad, expansive push-pull across a long 20-subdivision cycle.
Pattern — 20 subdivisions per cycle
Mute one layer to focus on the other. LCM = 20 subdivisions per cycle.
About 4:5
4:5 has an LCM of 20, creating a very long cycle before the two layers realign. Nine distinct attack points (4+5 minus coincidences). The interaction sounds like a slowly rotating rhythmic wheel — the patterns converge very rarely, which creates a hypnotic, shifting quality favored in minimalist and contemporary classical music.
LCM of 4 and 5 is 20 subdivisions per cycle. The layers realign less often than in simpler ratios.
Practice levels
Hear the combined pattern with visual highlighting
Start →Identify which ratio you're hearing from a short list
Start →Identify with one layer muted — hear the implied pattern
Start →Identify ratio, muted layer, and tempo simultaneously
Start →Examples in music
Various Minimalist Pieces
Steve Reich/Glass
Phase music exploits ratios like 4:5
Gamelan music
Javanese tradition
Multiple isorhythmic layers at different ratios