This post is one of a 2-part series of free basic music theory lessons on my blog, musictheoryde-mystified.com. You can see the complete list here. Please feel welcome to make a comment or ask a question.
The standard note values make it easy to to indicate lengths of half or quarter of a beat. This suits some rhythms but not all. Many others are based on dividing a beat into thirds.
Dividing A Beat Into Thirds
Rhythms based on 1/3 beat subdivisions have a slightly more lelaxed feel compared to semiquavers; they sound a little less intense…
That’s not to say that these rhythms can’t be powerful and driving!
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Compound Time
So how can we divide a beat into thirds of a beat when the standard note value symbols are based on halves?
We do this by using a symbol for 1 beat which naturally has 1/3 beat subdivisions, the dotted crotchet.
A dotted crotchet is the same length as 3 quavers.
- In simple time we count beats and half beats as ”1-and 2-and” etc.
- In compound time we count ”1-and-a 2-and-a” etc.
Time Signatures With A Dotted Crotchet Beat
To make a beat which naturally divides into thirds, we want the dotted crotchet, not the crotchet, to be the symbol for 1 beat. So how do we distill this into a fraction name?
A dotted crotchet = a crotchet + a quaver. As a fraction, that’s 1/4 + 1/8 = 3/8. The dotted crotchet is a 3/8 note.
Time signatures are written as the number of beats in a bar x the note value for 1 beat.
- A bar of 2 dotted crotchet beats is 2 x 3/8 = 6/8
- A bar of 3 dotted crotchet beats is 3 x 3/8 = 9/8
- A bar of 4 dotted crotchet beats is 4 x 3/8 = 12/8
And so on…
Review: Time Signatures In Simple Time
Time signatures are fractions. In simple time, the upper note, the numerator, represents the number of beats in a bar and the lower note, the denominator, represents the name of the note value which represents 1 beat.
Split up, a time signature in simple time looks like this:
3/4 = 3 x 1/4 note (crotchet) beats per bar
Other note values can also be used to represent 1 beat. For example,
4/8 = 4 x 1/8 note (quaver) beats per bar
2/2 = 2 x 1/2 note (minim) beats per bar
Reserved Time Signatures
When we see a time signature like 6/8 we would normally assume that there are 6 beats in the bar, each of which is a quaver (1/8 note). However, 6/8 and higher multiples of 3/8 (not 3/8 itself) are reserved for music which requires a dotted crotchet beat.
These time signatures aren’t what they appear to be; they need to be broken down to be understood. Appropriately, they are collectively known as compound time.
It takes a little while to get used to reading music in compound time. We’re so used to seeing a crotchet as 1 beat that it’s hard not to think of a dotted crotchet as 1 1/2 beats…
The trick for reading compound time is to think of each dotted crotchet as a fast bar of 3. More on this later…
Hierarchy Of Compound Time
Bars have strong and weak beats. This is true for both simple and compound time. The only difference is whether a beat naturally divides into halves or thirds.
Below are the hierarchies of strong and weak points in 6/8, 9/8 and 12/8.
How To Read And Play Compound Time
In simple time, we can make a piece easier to learn by slowing it to half the tempo and counting every half-beat as a beat. For a reminder, please visit 3. Beats, Tempo and Timing.
In compound time, the same method would have us slow down to 1/3 of the tempo so each quaver can be counted as a beat. Practically, we don’t need to slow down quite so much, but the principle is the same.
Think of each dotted crotchet grouping as a miniature bar of 3 quaver beats, a bar of 3/8. Three beats per bar at a fast tempo is familiar to many as a waltz. If you know what a fast waltz feels like, you’re well on the way… if not, practice each dotted crotchet’s worth of notes as a separate bar of 3 until you feel the rhythm.
Once you can feel character of each beat of 3/8 as a simple 3-beat rhythm, you can start to speed up the tempo a bit until each bar of 3/8 feels like a beat in the overall time signature.
For example,
Zoom in a little. Think of each beat as a bar of 3.
It may look more familiar if we rewrite it as 3/4. Simply double each note value.
If you’re familiar with simple rhythms in 3/4, you’ll be able to play them at the tempo of a fast waltz.
Tap, clap or play along:
3/8 has the same beat structure as 3/4, it just looks different. Just count quavers as beats instead of crotchets…
Once you’re used to the character, increase the tempo until it’s quite fast, say 180 bpm.
As you speed up, you’ll start to feel each group of 3/8 as a single beat.
Once you feel the character of the whole rhythm, you can increase the tempo further if needed.
In the next lesson we will look at some common rhythms in compound time.
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* Audio extract from Another Hopeless Situation by Erik Kowarski
NEXT LESSON: B9. How To Read Rhythms 2: Compound Time
PART 2 CONTENTS: Basic Music Theory Course Contents