Duple Metric Structure
A duple metric structure has pulse streams related in 2:1 proportions, with each stream arranged in a strong-weak accent pattern. Sometimes, a 4:1 proportion is strongly communicated between two (visually) non-adjacent levels of pulse. Also, the accents that produce the strong-weak pattern may themselves vary in strength.
Listen to the last movement of Haydn’s Symphony #101. Example 25 represents the four easiest-to-hear pulse streams of this duple metric structure with dot notation:
Choosing a note value for one of the pulse streams will then determine the note values of the remaining three. In Example 26 below, the quarter note has been chosen to represent the level C; this fixes the note values for all the other levels. What would the note values of the other levels be if the quarter note was chosen to represent level B? or level D?
Choosing a Beat and its Note Value
Listen again to the beginning of the Haydn and decide which pulse stream you hear as the beat. Although we often think of the quarter note as representing the beat, it is not always so. Given the quarter note as level B, it is likely that you will NOT choose it as the beat. Let’s examine the options. Remember that the level and note value you choose to be the beat must allow for the other levels you hear to be represented. For instance, if you choose level D and the eighth note as beat:
there should be several slower pulse streams represented in the metric structure.
If you choose the quarter note,
you should be able to hear and tap two slower pulse streams and one faster.
If the half note is chosen,
two faster pulse streams and one slower stream should be easy to hear.
If you choose the whole note as beat, you must ask whether this level is itself grouped in two’s or three’s. This would require your adding a level above level A to show the strong-weak pattern:
This level may be relatively difficult to hear and tap; but its function, to show the pattern of the whole note stream as strong-weak, is essential. In this movement, the whole note is easily counted as the beat.
Choosing a time signature for duple metric structure
There are several possibilities for a choice of time signature using the notation in the above examples, since they contain note values represented by the common bottom numbers in time signatures: 2, 4, and 8. We know from experience that 2/4 and 4/4 are very common signatures, and
might also appear as the signature. 4/8 or 2/8 or even 4/1 are possible, though unlikely. It turns out that Haydn chose cut time (see the score in Burkhart, 5th ed., p.166). “4” or “8” could have served as the lower number in the signature; there is no way to tell specifically from the sound. It was conventional at the time to use cut time for very fast tempos, but other signatures representing this metric structure at the same tempo occur frequently as well.
Should we at least be able to decide whether the music is “in 2” or “in 4”? There may be clear evidence in the sound—a “boom-chick” accompaniment may suggest “2” as the top number for a signature and “boom-chick-chick-chick” may suggest “4” as the top number. But it is often difficult to discriminate between a duple and quadruple grouping, since a quadruple group is a double duple group; i.e., quadruple is a compound of duple. This can be seen in Ex. 31, where the beat pulse is indicated by the arrow: