In musical terminology, a cluster denotes a range of simultaneously sounding pitches that may change over time. The set of available pitches to apply usually depends on the accoustic source. Thus, in piano music, a cluster typically consists of a continous range of the semitones as provided by the piano's fixed set of a chromatic scale. In choral music, each singer of the choir typically may sing an arbitrary pitch within the cluster's range that is not bound to any diatonic, chromatic or other scale. In electronic music, a cluster (theoretically) may even cover a continuous range of pitches, thus resulting in coloured noise, such as pink noise.
Clusters can be denoted in the context of ordinary staff notation by engraving simple geometrical shapes that replace ordinary notation of notes. Ordinary notes as musical events specify starting time and duration of pitches; however, the duration of a note is expressed by the shape of the note head rather than by the horizontal graphical extent of the note symbol. In contrast, the shape of a cluster geometrically describes the development of a range of pitches (vertical extent) over time (horizontal extent). Still, the geometrical shape of a cluster covers the area in wich any single pitch contained in the cluster would be notated as an ordinary note. From this point of view, it is reasonable to specify a cluster as the envelope of a set of notes.
A cluster is engraved as the envelope of a set of
cluster-notes. Cluster notes are created by applying the function
notes-to-clusters
to a sequence of chords, e.g.
\apply #notes-to-clusters { <c e > <b f'> }
The following example (from
input/regression/cluster.ly
) shows what the result
looks like:
By default, Cluster_spanner_engraver is in the Voice context. This allows putting ordinary notes and clusters together in the same staff, even simultaneously. In such a case no attempt is made to automatically avoid collisions between ordinary notes and clusters.
input/regression/cluster.ly
,
Cluster_spanner_engraver, and ClusterNoteEvent.
Music expressions like << { g8 e8 } a4 >>
are not printed
accurately. Use <g a>8 <e a>8
instead.
This page is for LilyPond-2.0.1 (stable-branch).