Duplets in 8 Time Signatures
Duplets. What exactly is a duplet? Duplets are the opposite of triplets. Triplets are always interpreted as three notes in the time of two. In other words, three eighth note triplets will take up the same amount of time as two normal eighth notes. Duplet values, on the other hand, are interpreted as two notes in the time of three. When you run across a set of eighth note duplets, they will have the same value as three normal eighth notes.
If this concept is a new one for you, you may wonder why a composer would want to write duplet figures. When working in simple meters such as 2-4, 3-4, or 4-4, you'll rarely encounter duplets, as quarter notes are normally broken down into two eighth notes at the first level of subdivision. The whole reason that simple meters are classified as "simple" is that beats are normally divided by units of two. In duple meters, quarters are divided in two to get eighths, eighths are divided in two to get sixteenths, and so forth. But what about compound meters? In compound meters such as 3-8, 6-8, 9-8 or 12-8, the larger beats are broken down into units of three divisions.
Look at example 1. Here you see four measures of 6-8 time. The first bar, consisting of two dotted quarters, reinforces the two main beats that form the larger rhythmic structure of this meter. The second measure, six eighth notes, would be played by placing a stroke on each count of the bar. By looking at these first two measures, you can see that the "beat" in a compound meter is the value of a dotted quarter note, and each dotted quarter can be divided into three equal parts by using eighth notes.
The third measure of this example contains the eighth note duplets. Each set of duplets has the same value as three eighth notes and divides the dotted quarter into two equal parts. Again, like triplets, duplets are an example of "false notation". The composer is telling you: "Two eighths don't really equal the value of a dotted quarter, but let's pretend that they do." Notice that the syllables written under the duplets don't correspond to the six counts that are in the measure. Keep in mind that 6-8 time might have six counts, but there are only two main beats in each measure. When confronted with having to play duplets, the easiest way is to slide into a feeling of two beats to the measure. When you feel that there are two beats in the bar, then imagine that you're playing normal eighth notes in a simple meter - in this case, 2-4.
To see where the duplets actually fall within the measure, take a look at example 2. The upper voice, written on the third space of the staff, shows each sixteenth in a measure of 6-8. Normally, these sixteenths would be counted as shown in the example. The lower voice illustrates that the duplets would fall on every third sixteenth. In essence, a measure of eighth note duplets asks you to divide six counts into four equal parts. A little math (or a little pocket calculator) will tell you that each of the duplet notes would equal one and a half counts. In other words, each duplet has the value of three sixteenth notes.
There already exists a notational symbol that has the value of three sixteenths: the dotted eighth. Take a look at example 3. Here you see two measures that are actually the same in every respect. The first bar uses the false notation of the duplets while the second employs the figure of the dotted eighth. So, if these two bars are exactly the same, why bother with duplet figures? Good question. Many composers feel that the duplets will sound smoother and more relaxed. Dotted eighth notes require performers to subdivide down to the level of sixteenths so they can keep track of all the numbers along with the "and" syllables. This means that each main beat will have to be divided into six parts. The duplets simply ask the performer to divide each beat into two equal parts. Which would you rather do?
Example 4 poses another problem. In the second measure, you see a set of four sixteenth notes with the duplet figure above them. I'm sure you're wondering why there is a "2" above these notes rather than a "4". Just like triplets, which are always "three in the time of two", duplets are always "two in the time of three". By using the number two above these notes, you are being asked to play two sixteenths in the same amount of time as three normal sixteenths. In the case of the second measure, the four duplet sixteenths are going to take the same amount of time as six regular sixteenths: one full beat, or the value of three eighth notes.
If you have a handle on the second measure of the example, the third shouldn't present much of a problem. To perform this measure, keep the feeling of two beats per bar and imagine that you are playing a 2-4 meter instead of 6-8.
The last example really brings home the relationship of 6-8 meter when duplets are used, compared with 2-4 meter using triplets. The lower line of the example progresses from one division per beat, through two, three and finally four divisions. Since this line is in a simple meter, the figure of three divisions requires the triplet notation. The upper line of this example also progresses from one to four divisions per beat, but since it is written in 6-8 time, the second and fourth measures require duplet notation. Each line will sound exactly the same
Most often, triplets and duplets are used whenever a composer wants to change the feeling and impression of the meter. By playing a series of triplets in a simple meter, the perception of compound meter is achieved. The reverse holds true for a series of duplets in any compound meter.