We’ve seen how, when music has a “pulse,” this regular pulsation can be used as a time scale for specifying onset timing by means of equally spaced “beat lines” (see Beats). However, for most music, a succession of identical beat lines is not enough to capture the way musical time is organized. That’s because most music is structured by regular pulsation at more than one rate. What we have been calling the “beats” is only one such rate of pulsation.
For example, if you are tapping your foot to some music at a moderate rate, you will often find that you can also choose to tap twice as fast, or twice as slow. If each of these possible foot-taps is represented by a dot, the pattern of pulsation could be visualized as three rows of dots. (This is a diagram for illustration, not a piece of global notation.)
Depending on the music, you may find that it is easier to tap three times as fast or slow (or some other number), rather than two. Or you may find that the most natural tapping rates are twice as fast and three times as slow, or vice versa. This depends on the way the different rates of pulsation are related to each other in the music. For example, the fastest rate of pulsation might be twice as fast as the “moderate” rate, while the slowest rate is three times as slow.
The way in which the different rates of pulsation relate to each other is called the “meter” of the music.
There may also be more than three rates of pulsation—in fact, there may be any number. But three is enough to introduce the concepts that are needed for specifying the grouping and division of “beats” in global notation.
From now on, we will use the term “pulse” only for the fastest rate of pulsation that is sustained reasonably consistently in a piece of music. We will continue to refer to the “moderate” rate as “beats.” A slower rate of pulsation corresponds to what musicians call “bars.”
If beats are regularly grouped into larger units called “bars,” we need some way of representing the “bar” level of pulsation in the score as well. As with beats, global notation represents this pulsation by using equally spaced vertical lines, but in this case the lines are drawn longer and if possible bolder than the beat lines, making them more visually prominent. (They should still, however, be less bold than the lines in the rotated T symbol for sounds of specified duration.) Since they work more or less like the “barlines” of staff notation, we will call them “bar lines.”
In the above diagrams, it will be seen that every pulse at a “higher” level coincides with one or more pulses at lower level(s). In the same way, every bar line is also a beat line in that it indicates the presence of a beat—specifically, the first beat of the bar.
Thus, if the beats are organized in regular groups of (say) three, the first of every three beat lines will be replaced with a bar line. The number of beats per bar is written as a plain figure (without the @ sign) above a bracket extending from the first to the second beat line.
If desired, tempo can also be specified as explained for beats, writing the tempo figure after the figure for the number of beats per bar. (see Beats). For example, writing “3@126” above the initial bracket would mean “3 beats per bar at a tempo of 126 beats per minute.”
Also if desired, bar numbers can be written either above each bar line or above the first bar line in each system.
Into such a grid, once more, can be placed symbols for sounds of either specified or unspecified duration. For instance, we could notate the beginning of a rock song where one member of the band counts the others in: “One, two, three, four.” As this implies, rock music normally has four beats to a bar, so the first of every four beat lines will be a bar line. Although the human voice produces sustainable sounds, this counting-in is usually done in a clipped, staccato way, where the duration of each syllable doesn’t seem important, so we will leave duration unspecified in the score. (Spoken or sung words can be written under the relevant layer, as in staff notation.)
Although we haven’t yet covered how to specify pitch, we could now notate the rhythm of a song, specifying both onset timing and duration in relation to beat and bar lines. For example, the rhythm of the children’s song “Twinkle, Twinkle, Little Star” (also known as “The Alphabet Song”) could be notated, leaving pitch unspecified.
In this case, the words are sung in a connected, legato way, without silences between them except where the singer takes a breath between lines, so the T symbols mostly touch each other, forming continuous lines.
Note how the thicker lines of the T symbols are placed over the thinner beat and bar lines. The difference in thickness leads to another principle for the placement of symbols in global notation:
With discrete shapes (such as the wedge), it’s the left-hand edge that counts;
with lines, it’s the center of the line that counts.
That is, as we saw earlier, for sounds of unspecified duration it’s the left-hand edge of the wedge that specifies the moment of onset. But as the T symbol is formed of two thick lines, the moment of onset for sounds of specified duration is indicated by the center of the vertical line, not its left-most extremity. When this line is drawn over a beat or bar line (with the same center), it indicates that the sound begins on that beat, not slightly before it as might appear. This convention makes the notation easier to write.
So far we have been limited to examples in which every onset falls on a beat. But in most music, many of the onsets fall between the beats, so we’ll need to be able to notate that too.
Next: Beat division