Additive rhythm builds unusual time signatures by combining groups of 2 and 3 eighth-note cells

In Western divisive rhythm, time signatures are generated by subdividing a regular beat into 2s or 3s. Additive rhythm works oppositely: it builds up a bar from short cells of 2 or 3 eighth notes. Combining two cells gives possibilities like 2+2=4, 2+3=5, 3+3=6 eighth notes per bar. Three cells give 8 possibilities. This generates asymmetric time signatures: 5/8, 7/8 (2+2+3, 2+3+2, or 3+2+2), 13/8. Additive thinking is common in Indian and Eastern European folk music.

Examples

7/8 = 3+2+2 or 2+3+2 or 2+2+3. 5/8 = 3+2 or 2+3. The tresillo pattern (3+3+2) is an additive rhythm that fits within 4/4.

Assessment

Write out all possible groupings of 2s and 3s that produce 7 eighth notes. Compose a 4-bar loop in 7/8 using one of these groupings.