Lesson 3.5 - Compound Time

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Up until this point, the only time signatures you came across were in SIMPLE TIME. This means that the beats can be divided in two. e.g. a crotchet can divide into two quavers, a minim can divide into two crotchets etc.

Now you will learn about COMPOUND TIMES where the beats divide into threes. "6/8 time" literally means that there are 6 quavers in a bar, but there are not 6 beats in a bar. Instead there are two dotted crotchet beats in a bar and each dotted crotchet is worth three quavers. Look at these two examples

In the first example notice how the quavers are grouped in threes and the beats in the second bar are dotted crotchets. In the second example there are still six quavers in the bar, but they are grouped in twos, and the beats are crotchets.

The other time signatures you will come across in Grade 3 ABRSM and Trinity are

• 9/8 = Three dotted crotchet beats in a bar
• 12/8 = Four dotted crotchet beats in a bar

There are three more words that you should know, 

duple, triple and quadruple. 

Their meaning is quite obvious, 

• duple time means 2 beats in a bar
• triple time means 3 beats in a bar
• quadruple time means 4 beats in a bar

Examples:

• simple triple time would be 3/4
• compound quadruple would be 12/8

There are two more things to be aware of in preparation for an examination with regard to compound time. The first is how to convert a tune from simple time to compound time. Look at these two examples

Both of the above tunes sound exactly the same even though they have different time signatures.
You will notice, to convert:

• from simple to compound - Lose triplets / Add dots
• from compound to simple - Add triplets / Lose dots 

Finally, you need to bear in mind is how to group notes and rests together in compound time. The main rule is group things together a beat at a time. Lets consider these four bars

1. In the first bar, notice how the 4th quaver is not joined to the other three, because it is part of a different beat.
2. In the second bar, a dotted minim can be used for two beats.
3. In the third bar there are two separate quaver rests - that is, not joined to make a crotchet rest, because each quaver rest belongs to a different beat.
4. In the last bar there are separate semiquaver rests, It is true that 2 semiquavers could be replaced by a quaver rest but composers  prefer to finish one quaver at a time i.e. the 1st semiquaver note and semiquaver rest make one quaver, then the next semiquaver rest and note make the next quaver. It is also easier for the performer to read.

One FINAL thing (I know - this was a long one) - just like in 4/4 time you should only use a minim in the first half or second half but NOT the middle two beats, so also in 12/8 time a dotted minim should not be used for the middle two beats. In the examples below, bars 1, 2 and 4 are correct, but bar 3 is NOT correct.

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