Specified onset timing
We have considered reasons for and against specifying sound sources, pitch, and duration in various situations (see Sound sources; Unspecified pitch; Unspecified duration). But one thing that we will nearly always want to specify about musical sounds is when they happen. In music, what matters is not just in what order the sounds happen (as with speech sounds), but how far apart in time. Above all, what matters is when each sound begins: that is, its “onset timing.” Even in music without a regular “beat,” onset timing is usually so vital to the effect that it is worth specifying with some precision in any score.
In global notation, therefore, onset timing is specified by default. However, as with other parameters, there are ways of leaving it unspecified if preferred.
It is important to remember that onset timing is not the same as duration. A sound does not necessarily continue until the onset of the next sound from the same source, so the length of time between the onsets of two successive sounds should not be equated with the duration of the first sound. Nor does the insertion of “rests” between the two sounds necessarily solve the problem, since it still requires one to specify the duration of the first sound—which, in the case of impulsive sounds, can be a moot point, as we’ve seen (see Unspecified duration).
Staff notation specifies onset timing only indirectly, by means of symbols that directly specify the durations of sounds and silences—“notes” and “rests” respectively. But as global notation allows for the option of leaving duration unspecified, it must specify onset timing independently of duration. This also has the advantage of making “rests” unnecessary: where there is no sound, nothing need be written.
Most often, onset timing is organized in relation to a steady beat or pulse that runs through the music. But not all music has a regular pulse, so global notation provides ways of specifying onset timing both with and without a pulse.
For simplicity, the specification of onset timing is introduced here using examples with unspecified pitch only. The same principles will be applied in contexts of specified pitch after the specification of pitch has been introduced.
Next: Pulseless onset timing