Compound Meters
After this lesson, you'll recognize the twelve compound meters and write their time signatures, and you'll understand why the bottom number stands for one third of a beat.
A compound meter is one in which each beat is always worth a dotted value: a dotted whole note, a dotted half note, a dotted quarter note or a dotted eighth note. Each beat therefore divides by three, so these are compound beats.
What the two numbers tell you
Here is the twist: a dotted value can't be written as a single number. That is why, in compound meters, the bottom number shows the value that fills one third of a beat. It can only be 2, 4, 8 or 16:
| Bottom number | It stands for | One third of a beat worth |
|---|---|---|
| 2 | a half note | a dotted whole note |
| 4 | a quarter note | a dotted half note |
| 8 | an eighth note | a dotted quarter note |
| 16 | a sixteenth note | a dotted eighth note |
The top number shows how many thirds of a beat fill the measure. Since these meters only have two, three or four beats, it can only be 6 for two beats, 9 for three beats or 12 for four beats.
Take 12/4 as an example. The whole measure needs twelve quarters of a whole note, that is, twelve quarter notes. Since each quarter note is one third of a beat, the meter has four beats, and each beat is filled by three quarter notes, which make a dotted half note.
Table of the twelve compound meters
| Value of one beat | 2 beats | 3 beats | 4 beats |
|---|---|---|---|
| a dotted whole note | 6/2 (six-two) | 9/2 (nine-two) | 12/2 (twelve-two) |
| a dotted half note | 6/4 | 9/4 | 12/4 |
| a dotted quarter note | 6/8 | 9/8 | 12/8 |
| a dotted eighth note | 6/16 (six-sixteen) | 9/16 (nine-sixteen) | 12/16 (twelve-sixteen) |
The most common ones
The ones you'll meet most have a dotted quarter note per beat: 6/8, 9/8 and 12/8. Others, such as 6/4, are also used now and then.
- Meter
- 6/8: compound meter
- Beats per measure
- 2 beats
- Beat unit
- dotted quarter note
- Beat division
- triple: 3 eighth notes per beat
- Reading the numbers
- 6 = number of beat-thirds; 8 = the eighth note, one third of a beat
- Corresponding meter
- 2/4 (simple: top ÷3, bottom ÷2)
- Strong beats
- beat 1 strong, beat 2 weak
Write the time signatures for these fragments, which are all in compound meter.