expert · LCM = 21
Three against seven — one of the most dissonant common ratios.
Pattern — 21 subdivisions per cycle
Mute one layer to focus on the other. LCM = 21 subdivisions per cycle.
About 3:7
3:7 creates an LCM of 21 with 10 distinct attack points. The 3 and 7 layers feel almost completely independent until they converge at the end of the 21-subdivision cycle. This is the territory of advanced notation-based composition rather than improvisation.
LCM of 3 and 7 is 21 subdivisions per cycle.
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
Spectral Music
Murail / Grisey
Ratio-derived time structures