Audio: tone cluster (0:04)
tone cluster plays four pairs of tone clusters on a piano. The tone cluster figure shows the score:
A tone cluster is a cluster of tones, or notes, that follow each other in a scale.
A tone cluster usually has a minimum of three notes. It is constructed from consecutive notes in a scale.
Any scale can be used to write a tone cluster. Any number of notes from that scale can be used to write a tone cluster.
One way to look at a tone cluster is as an example of pandiatonicism. This term is associated with functional harmony. It means that, whilst the notes are diatonic to a scale, the chord does not have any of the functions associated with diatonic and chromatic chords in functional harmony. All the notes in the tone clusters in tone cluster are taken from a scale. The first pair of chords are tone clusters in a major scale, the second pair are chromatic tone clusters, the third pair contain all five notes in a pentatonic scale and the fourth pair contain all the seven notes in a mode.
Another way to look at a tone cluster is as an application of the chord scale system in jazz harmony. This enables the notes in each chord in a progression to be constructed from different scales.
A further interpretation of a note cluster is as a chord constructed from the notes in the chromatic scale. This scale is probably the most widely used scale for tone clusters.
A tone cluster is often perceived as dissonant. However, if the outer notes of a tone cluster form a consonant interval, some listeners perceive the sound as more consonant than dissonant.
A tone cluster has ambiguous tonality. It is used in harmony as an ambiguous sounding chord, as a dissonant sounding chord, as an embellishment in a piece consisting of consonant chords, or as an unpitched sound akin to noise.