Pulseless onset timing
To decide how to specify onset timing in your score, the first question to ask is whether the music has a regular “pulse” or not.
If you can tap your foot to the music, it probably has a pulse, even if you are tapping very slowly or at a fluctuating rate. If you can’t detect a pulse in the music, you can still specify onset timing by using a linear scale of time as measured by the clock, in minutes and seconds.
A given unit of length along the horizontal axis should be assigned to a given unit of time, for instance 1cm = 1 second. The time scale to use will depend on the density of information to be included in the notation: for instance, the maximum number of onsets per second. The time scale can be indicated above the beginning of the score with a kind of horizontal bracket which (from its appearance) we will call a “hurdle.”
If you don’t wish to specify onset timing, but only the order in which the sounds happen, you simply don’t draw a hurdle. The absence of a hurdle will indicate that no proportional time scale applies, and the symbols for sounds can be spaced simply according to convenience of reading. Duration will necessarily be unspecified, although the rotated T symbol that normally indicates a sound of specified duration can still be used to indicate a sustained sound or one that is connected to the next sound without a break.
When onset timing is specified, the hurdle can take various forms depending how much of the music it applies to; see Variable beat division. Most often it will apply to all of the music until further notice, in which case it has a double horizontal line with the end lines pointing down.
Symbols for sounds of either specified or unspecified duration can be spaced along the layer line(s) according to their onset timing. The left-hand edge of each symbol represents the onset of the sound, while for sounds of specified duration, the right-hand edge represents the end or “release” of the sound.
For our first actual score, we will use an example of a single drum playing a series of strokes of indefinite pitch without a discernible pulse.
Since the drum sounds are impulsive and die away rapidly without the player’s control, their duration is left unspecified by representing them with “wedge” symbols. Since they have no definite pitch, and only one kind of sound is used, all the wedges are placed directly above the layer line. Onset timing is specified by the horizontal spacing of the wedges, showing a gradual but uneven acceleration. As the strokes come closer together, the wedges start to overlap, but their left-hand edges are still visible, specifying the timing of each onset. For this score, the onset timing was determined with the aid of sound analysis software; see Measuring onset timing with a waveform graph.
Most music, however, does have a pulse, and in that case we can specify onset timing in relation to the pulse rather than the clock.
Sources of audio
"Woodo-kut” from Samul-Nori: Drums and Voices of Korea (Seoul: Oasis Record Co., ORC-1041), track 2.