Simple meter (or simple time) is when the beats of a piece of music can be divided into twos, whereas compound meter (compound time) is when the beats divide into threes. This definition of simple and common meter is quite straightforward, but the application of it requires some thought.
A piece with a time signature of 3/4 has 3 crotchet (quarter note) beats in every bar.
Each crotchet beat can be divided into 2 quavers (eighth notes) and so it is in simple meter or simple time. There are a total of 6 quavers in a bar arranged in twos across 3 beats.
On the other hand, a piece that is in 6/8 has the same total of quavers in a bar as 3/4 (6 quavers), but 6/8 implies that the quavers are grouped together in threes to form 2 dotted crotchet beats.
As a result, the piece is in compound meter or compound time.
If you watch someone conducting in 6/8 time then you will see that they will actually be counting “1 – 2” for each bar.
Examples of Simple and Compound Meter
The other descriptive words that can be combined with the words “simple” and “compound” are duple, triple and quadruple – these words simply describe whether there are 2, 3 or 4 beats in a measure (bar).
Simple Duple Meter
So, for example simple duple meter may sound complicated but it just means that there are 2 beats (duple) in every bar and each beat can be divided into two (simple).
Simple Triple Meter
In simple triple time there are 3 beats (triple) in every bar and each beat can be divided into two (simple).
Simple Quadruple Meter
In simple quadruple time there are 4 beats (quadruple) in every bar and each beat can be divided into two (simple).
Compound Duple Meter
Compound duple meter means that there are 2 beats in a bar (duple) and these can be divided into threes (compound).
Compound duple time always has the number 6 at the top of the time signature.
Examples include 6/8 and 6/4.
Compound Triple Meter
Compound triple meter means that there are 3 beats in a bar (triple) and these can be divided into threes (compound).
Compound Quadruple Meter
Compound quadruple meter means that there are 4 beats in a bar (triple) and these can be divided into threes (compound).