Chapter four: compound meters
Meter signatures
The top number of the meter signature is 6, 9, or 12, representing duple, triple, or quadruple meter. Divide this by three to get the number of beats per measure (two, three, or four). The lower number is usually 8 but may also be 4 or 16. This number shows the type of note that represents the division of the beat. Add three of these note values to get the beat unit, which will always be a dotted note. Below is an example of compound meters:
Mixing beat divisions and groupings
In simple meters, the beat may occasionally be divided into three parts instead of the normal two. These beats, marked with a 3, are called triplets.
When notating triplets, use the same duration values for the triplet as the duple division it replaces. An eighth note triplet replaces two eighth notes, and a sixteenth note triplet replaces two sixteenths.