Compound Time Signatures (6/8, 9/8, 12/8)
Time signatures where each beat divides into three — the lilting swing behind jigs and many ballads.
Explainer
In compound time, each main beat divides naturally into THREE, not two.
6/8 has two main beats per bar (each worth a dotted crotchet = 3 quavers). 9/8 has three main beats. 12/8 has four main beats.
The bottom number (8) means the quaver is the basic unit being counted, but the FEEL is in groups of three quavers per beat — giving compound time its rolling, lilting feel.
Worked examples
Example 1
6/8 — two beats per bar
Two groups of three quavers: ONE-and-a, TWO-and-a.
Example 2
9/8 — three beats per bar
Three groups of three quavers: ONE-and-a, TWO-and-a, THREE-and-a.
Example 3
12/8 — four beats per bar
Four groups of three quavers — the same rolling feel as 6/8, just twice as long.