9. Duplets

We have already learnt about triplets in music. Just to refresh your memory, triplets are used when we want to play three notes in the space where there would normally be two:

The triplet (circled here) is marked with a "3".

Triplets are very commonly seen in simple time signatures, when the composer wants to split the main beat into three, instead of two.

Duplets work in a similar way - but instead of writing three notes in place of two, we use a duplet to write two notes in place of three:

This example is in 6/8. Normally the dotted crotchet (quarter note) beat would be divided into three quavers (eighth notes), like in the first bar. The duplet is used in the second bar, to divide the dotted note into just 2 quavers. It has the effect of making them a little bit slower than the regular quavers.

Click on the "play" button, to hear the duplets being played against a steady quaver (eighth note) beat:

Try singing along, so you get a feel of how the duplets need to be slowed down!

Duplets are very commonly seen in compound time signatures, when the composer wants to split the main dotted beat into two, instead of three.

Questions about Duplets

In the grade four exam, there will probably be one or two questions which involve duplets or triplets.

• You might be asked to give the meaning of the symbol - for duplets, write "play 2 notes in the time of 3," and for triplets, write "play 3 notes in the time of 2."
• You might see duplets or triplets in the composing a rhythm question (see lesson 10).
• You might be asked to rewrite a bar or two of music, changing it from compound to simple time, or vice versa. This usually involves some triplets and duplets. (Read on for more!)

Rewriting a Rhythm in a New Time Signature

It's possible to change the time signature of a piece of music without changing the rhythmic effect. This means that the rhythm sounds the same.

There are three basic ways of doing this:

1. make all the note values twice as long
2. make all the note values half as long
3. change the time signature from simple to compound (or the other way round).

Let's take an easy 3/4 bar as an example:

1. Make all the note values twice as long.

First let's change the time signature. 3/4 means there are three crotchets (quarter notes) per bar. To make the note values twice as long, we'll need to put three minims (half notes) per bar, so the time signature will become 3/2. (Remember that the bottom number tells you what type of beats to count.)

Next, we simply write out the same notes, but make each one twice as long. A crotchet becomes a minim, (a quarter note becomes a half note), and so on:

2. Make all the note values half as long.

We'll need three quavers (eighth notes) per bar, so the time signature becomes 3/8.

Each note is re-written using a note half its value. A crotchet becomes a quaver, (a quarter note becomes an eighth note), and so on.

When we make the notes half as long, we often need to put some beaming in, as in this example. This means you'll also sometimes need to change the stem direction of some notes - we had to change the stem on the C here. It's a good idea to write all the note heads in first, without their stems, and then add the stems and beams at the end.

3a. Change the time signature from simple to compound.

Instead of having three crotchets (quarter notes) per bar, we'll need three dotted crotchet beats per bar. This means the time signature will become 9/8.

Each beat will become a dotted beat. In this case the beat is a crotchet, (quarter note), so we make these dotted.

Beats which are divided into two will need a duplet symbol added (because in compound time we would expect the beat to be divided into three).

Beast which are divided into three with a triplet sign, don't need anything added (because we already expect them to be in threes in compound time).

3b. Change the time signature from compound to simple.

Let's change this compound time, 12/8 example. 12/8 has four dotted beats.

Four undotted beats = 4/4.

Dotted beats become undotted.

Duplets become "normal" (nothing added).

Quavers (eighth notes) become triplets ("3" added).