V. meter and expression
Before we take up rhythmic notation, let us reflect on some of the expressive qualities of meter that we are likely to have experienced so far. First, the clarity or strength of measuredness itself represents a chief identifying feature of a piece of music and is an important part of the temporal character of a piece. Compare this quality in the Sousa and Debussy examples, both of which are notated using standard symbols; yet Debussy’s rhythms sound much more unmeasured. The Chopin excerpt demonstrates how rubato can be applied to give expression to specific parts of each phrase. Although fairly strictly measured, the Beethoven Symphony and Pink Floyd’s Money both sound more unmeasured at first. Pulse streams are introduced gradually, producing an emerging metric structure. Compare this expression of the metric structure to the Sousa march, where all the pulse streams are introduced nearly simultaneously. Emergent metric structure can be heard in the mbira example as well.
Dilmano, dilbero and the C Major Prelude both illustrate a still more subtle expressive quality of metric structure. If you attempt to count at a steady (and fast!) tempo for the Bulgarian song, you will find yourself counting in groups of two’s and three’s: (1-2)(1-2-3) (1-2) on the word, “dilmano.” However, this fast pulse is not expressed in the music itself. You are supplying it as a way to show the proportions of time given to syllables of the text: the accented syllables take up three counts, the unaccented, two. In other words, the durational patterns in the voices imply a fast regular pulse stream; the listened then makes explicit the groupings of 2's and 3's.
It is easy to count the pulse stream expressed by each note in the Bach Prelude in 4’s or 8’s. However, there is an implied pattern of alternating groups of 5 and 3 that is expressed in the music. While listening to this excerpt, try counting (1-2-3-4-5)(1 2 3) instead of a steady 4 or 8. What aspect of patterning allows this subtle grouping to be heard as an implied irregular pulse stream? Can you also hear the 8 pulse divided this way: (1-2)(1-2-3)(1-2-3)? The score in Example 19 may or may not help you determine this:
Ex. 19 J.S. Bach: Prelude in C, Book I, Well-Tempered Clavier
To sum up, we have noted four ways that meter contributes to the expressive qualities of music: the clarity of a measured pulse, the application of rubato, the gradual emergence of the pulse streams in a metric structure, the mixing of groups of different lengths and the potential for musical patterning to imply pulse streams that can be experienced by the listener. There are many more ways metric structures can contribute to expression. Most have to do with changes in the number of levels and the size of groupings within pulse streams, how prominent they are, and how the composer chooses to manipulate or exploit all these possibilities. Metric structure is an essential component of the character of a piece of music and contributes to its expressive condition at every moment of the music.