Introduction

We have already met a variety of time signatures in Time signatures level 1 and Time signatures level 2. However, there is an important group of time signatures which we have not yet encountered.

Time signatures

Do you remember the time signatures we have met so far, from 2/8 to 4/2? Whatever the type of beat, and however many beats to a bar, each of those beats always divides into two (unless we use triplets).

What if we want to write a whole piece with beats subdivided into 3? Do we have to write out triplets for every single beat? That seems inefficient!

There is a better way: we can also make time signatures in which the beats subdivide in 3, rather than 2. Time signatures with beats that divide in this way are called compound time signatures.

By contrast, those time signatures that you've already met - that have beats that divide into 2 - are called simple time signatures. 3/4, for example, is a "simple triple" time signature, and 2/8 is "simple duple time".

Compound time

So, if we have three notes to a beat rather than two, then what time signature do we end up with?

Well, let's consider what the "compound" equivalent of 2/4 looks like. Instead of 2 beats of a crotchet length each, with 2 quavers to a beat, the compound time version has three quavers to each beat.

So, for the two beats in the time signature, this means we have a total of 6 (3+3) quavers in the bar. And this is how we describe the time signature: 6/8, meaning that there are six quavers in the bar.

As 2/4 had two crotchet beats, then, so 6/8 has two dotted crotchet beats.

2/4: two crotchet beats
	( + )
6/8: two dotted crotchet beats
	( + )

Remember that we are counting the two dotted crotchet (three quaver) beats, and not the 6 quavers individually.

The time signature therefore no longer describes the number of beats and the type of beat. This is because we don't have a simple number (such as 2, 4, 8 as in 2/2, 2/4 or 2/8) for the dotted notes values, and we therefore have to describe it in terms of the quaver subdivisions.

Counting in 2/4 and 6/8

Duple, triple, quadruple

Just as with simple time, compound time signatures can have 2, 3, or 4 beats to the bar. 6/8, with two beats, is an example of a duple compound time signature, 9/8 is a triple compound time signature and 12/8 is a quadruple compound time signature.

Counting in 9/8 and 12/8

Notice how the patterns of strong and weak beats (illustrated by different size numbers in the example above) are the same in 9/8 and 3/4, and in 12/8 and 4/4.

3/8: Simple time

Notice that the first number in compound time signatures are multiples of 3 (the number of units to a beat):

• 6 = 2 x 3 (as in 6/8)
• 9 = 3 x 3 (as in 9/8)
• 12 = 4 x 3 (as in 12/8)

So is 3/8 a compound time signature too?

No! As a compound time signature it would be only one beat long (one beat of a dotted crotchet length) - and time signatures with one beat do not exist because there would be no "weak" beat to counter the "strong" beat, and the music would just be "strong,strong,strong,strong"!

So 3/8, like 3/4 and 3/2 is simple time signature, counting three quaver beats in a bar. All other time signatures with multiples of three as the first number (6/8, 9/8, 12/8, 6/16, 9/16, 12/16) are compound time.

Accents in compound time

Where do the accents - the "strong" and "weak" beats - fall within compound time signatures?

They are very similar to the strong and weak beats in simple time signatures. For a duple compound time signature such as 6/8, the first dotted crotchet beat is strong, and the second dotted crotchet is weak, just as in a duple simple time signature such as 2/4: "strong-weak".

The same rules apply for compound triple time signatures such as 9/8: "strong-weak-weak", just like 3/4, and compound quadruple time signatures such as 12/8 "strong-weak-medium-weak", just like 4/4.

A useful grid

In Time signatures level 2 we saw a useful grid summarising the duple, triple, and quadruple simple time signatures. Here is the same grid, but showing also the compound versions described above.

Beat length	2 beats duple time	3 beats triple time	4 beats quadruple time
simple: crotchet
compound: dotted crotchet

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Revision

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