Can someone elaborate on tone-clusters and what exactly makes a set of notes be considered a tone-cluster? How are they similar and how do they differ from chords? To the users that are thinking of going and pasting a link to Wikipedia or flagging my question because they feel like I haven’t put forth any effort “researching” the topic please don’t comment at all! I have been reading and watching videos for the past week but can fully grasp the topic.
Your confusion is understandable; there is certainly a gray area between tone clusters and extended chords where a group of notes could be viewed as both.
Since you've been looking for definitions already, I'll try to supply one of my own. To me, a tone cluster is a collection of three or more pitches that includes at least two consecutive half-step intervals and never has more than a second between consecutive pitches.
Consecutive half steps are relatively rare in tonal music outside a completely chromatic context. As such, something with two or more consecutive half steps would immediately signify a tone cluster to me.
Furthermore, the appearance of three simultaneous, consecutive pitches separated by second (major or minor) is pretty rare in tonal music. Someone could theoretically claim that it's, say, a ninth chord in third inversion (you would thus have the seventh, root, ninth, and third all in a row), but I think that's really stretching the limits of functional tonality.
Tone clusters are chords depending how you define chords. A tone cluster is just a chord made up of mostly seconds. Whether a chord is a tone cluster, a chord by seconds (a chord made by stacking major or minor seconds), or an inverted ninth chord is all dependent on context and can arguably be more than one of those depending what’s going on around it.
Tone clusters also do not need consecutive minor seconds. Some of the most useful clusters are the first five notes of any church mode. That being said tone clusters are usually divided into two categories: diatonic (meaning from the notes of major or minor scales or one of their modes) or chromatic (meaning all the notes).
According to Vincent Persichetti the top and bottom notes of clusters are the most important notes and form two melodies. Tone clusters also appear in uncontroversially tonal music. The first song of Kindertotenlieder by Mahler contains a three note cluster. After finishing a traditional tonal theory text I would highly recommend Vincent Persichetti’s 20th Century Harmony Creative Aspects and Practices. Henry Cowell’s book might also be helpful. Cowell and Charles Ives would have been among the first composers to use tone clusters.
Just to add a bit to @Richard's answer.
In common tonal harmony you often have intervals of harmonic seconds from things like inverted seventh chords or types of suspensions. For example
V2/4 moving to
I6, or a suspension like
C F G resolving to
C E G. But, notice how the seconds resolve to thirds. This provides tonal clarity so that the seconds sound like a dissonant, but harmonic interval.
You could look at seconds and clusters of seconds and ask if they are somehow resolving, being treated as dissonant chords. If they move freely, without resolving, then a cluster label starts to make more sense.
An example you might look into where the boundaries are blurred is D. Scarlatti. Ralph Kirkpatrick has a book about Scarlatti and devoted a section to what he calls harmonic superposition where elements like pedals, suspensions, and superimposed chords create cluster-like harmonies.
Tone cluster, note cluster, pitch cluster
To add further to answers... and not a conclusive answer...
... the term tone cluster occurs in phonology (seems to be about different vowel sounds in a multi-syllabic words. e.g.
to—ma—to has a tone cluster,
ga—ga doesn't ). Maybe the term is borrowed from phonology.
It occurs notably in piano music and I'd imagine orchestral music followed.
Cluster is a collective noun: cluster of grapes, cluster of diamonds, a cluster of stars.
Note you'd expect to find more than three of these things above. Cluster is like "around something", so I guess something already exists and other things "gather around it".
Tone cluster: does
tone here mean:
A (whole or half)
I.e. are we thinking:
To be clear here the language is confusing. To be certain, do the collocations
"pitch cluster" and
"note cluster" exist in the same context?
A search for "pitch cluster", shows:
Scales, Modes, and Chord/Cluster Concepts for 20th-Century Techniques Exam
[from Western Michigan University].
[e.g. A quintal pitch cluster etc..]
Elaine Gould in her Behind Bars consistently uses "note cluster" not "tone cluster" (and uses if freely between determinate and indeterminate pitch); so I would say that there is a school of thought that says that "note cluster" and "tone cluster" are synonymous, but I choose to disagree and consider that they have separate but related meanings.
I will be brave and give some definition of what I think the terms could mean:
Note cluster: has indeterminate pitch, can't say it's exactly
c c# d d#, but give some range or location of the cluster.
Pitch cluster: has determinate pitch, can give exact note values e.g.
c c# d d#.
- Is it a general term that it includes the above two?
- Or has the tone cluster become to mean a cluster of intervals that mainly include a tone or semi-tone (because of the
tone = notevs
tone = intervalconfusion)?
But there's no question that tone cluster does mean a group of notes between a semitone and tone, probably with at least a semitone in the group.