Clusters

Most of my electronic music begins with the construction of sounds. I form some idea in my head and try it out in various guises, and ultimately I either discard it or decide to pursue it into a composition. The idea I began with in Clusters is, naturally enough, the idea of a cluster of tones. When I first tried this concept, I included sounds with complete spectra, such as you might find with a group of instruments or the piano playing a group of notes together. This led to very dissonant chords in which the mass of sound overwhelmed the perception of details. Then I decided to try putting together the tones as partials of a sound. I had written numerous compositions that were based on both harmonic and inharmonic partials, and sometimes these involved using sounds that were very close in pitch. The trouble then became that the spectra were not complex enough when they all remained within a single octave. When I extended the idea to duplicate the partials three and four octaves above the fundamental, then I began to get more interesting results, and that is the perspective from which I began composing the piece. To state the basic concept of the piece: the harmony, or the notes in the cluster, becomes the spectrum of the sounds.

The next step was to concentrate mainly on using pentachords as the basis of the clusters. I tried several different harmonies, based on trichords, tetrachords, and pentachords, but the latter were most interesting. Each group of tones had a kind of harmony that you could hear within the sound, and the contrast between one and another was good. But this was still only the beginning of the process. I then had to develop different ways of presenting the sounds in context.

There was one other problem I had to deal with, which is unique to using clusters of tones close together to each other in low octaves. Our ears do not hear sine tones very well in low octaves. Most of the rich tones created by bass instruments contain mainly higher partials. For tones in the octaves including middle C and below, I have added a small spectrum to the tones to give them some strength in their upper partials (just two partials in the Middle C octave, 4 in the octave below, and 8 in the octave below that). This is a very mild quality. We will see in one of the examples coming up that, even with this reinforcement, tones in the lower octaves still sound softer.

My experience in electronic music (and all music, for that matter, as far as sounds are concerned) is that sounds can be described mainly in terms of three classes of properties:

1. The spectrum or harmonic components, which are the partials that make up the sound; and all partials are sine tones. Composers of instrumental music are accustomed to structuring the pitch of sounds as the basis of most of their music, but electronic music composers have discovered that not all sounds even have the property of pitch; those that don’t include both noises and tones with inharmonic partials, which sound like (what else?) clusters.

2. The second property is envelope, or growth and decay characteristics, and here we mean not only the growth and decay of the entire sound but more accurately the growth and decay of the individual components of the sound. When all the components have individual envelopes, really interesting sounds can result.

3. The third property, deviations in tonal characteristics, is actually a group of qualities. Things rarely happen in a fixed manner in music; they are always changing. Deviations include qualities like vibrato, tremolo, pitch instability (not the same thing as vibrato!), detuning (or some would say intonation problems), dynamic changes, and other many things.

My approach to electronic music is to control and structure all of these qualities, and that is how I have learned to create interesting sounds.

Synthesizing sounds in compositions requires creating “instruments” that describe how the sound is to be generated, and I would like to describe the instruments I created for this piece. The first is the basic “cluster” instrument, which plays the bulk of the tones in the piece. First, it duplicates the tones of the cluster within a span of four octaves. Since there are five tones in the cluster, this means that there are 20 components. More importantly, each component has an envelope that makes it prominent over a separate portion of the duration, so that there is a constant shift of emphasis of which component you hear. I call this process a “shift function.” These are arranged in ascending order in a cycle which repeats twice over the duration of the tone. Finally, there is a crescendo and diminuendo applied to all of these tones. The first example which I will play is a cluster of 01346 [* counting in semitones above the lowest note; from C, this would include C, C#, D#, E and F#] applied to a middle C. (All of these examples come directly out of the piece.) You hear the a kind of “shimmer” that goes up, reaching the top of the spectrum in the middle of the note, when it is loudest; but at that spot you can already hear the lowest components returning, and the cycle repeats as the tone dies away. The duration of the tone is 18 seconds. [Example 1]

The next instrument, which I call “woosh,” has clusters of only three octaves and thus fifteen components, but each of the partials is attacked individually. There is only one “cycle,” and after being attacked the tones simply fade away in the same order as they were attacked, overlapping one another. This instrument is always used on shorter notes. The example I have is an A above middle C, the cluster is 02358, and the duration of the tone is 9 seconds, half of the previous tone. [Example 2]

Interestingly, these sounds are most effective when they are above middle C. Lower sounds are very different. Here is an example: The pitch is E-flat below middle C, the cluster is 01346, and the duration is also 9 seconds. It is important to recognize that the processes in each of these examples are the same. [Example 3]

The third instrument which I created produces a glissando (actually a vibrato, except that it is so slow that it sounds like a glissando). There are three octaves’ worth of components, and they have the same shift function and crescendo-diminuendo as the notes in the cluster instrument, except that there is only one cycle over the course of the duration. After a delay of one-fifth of the duration, to establish the pitch, the components begin a very slow glissando up and down in the pattern of a sine wave, completing just one cycle. The first tones that do this only go up and down by a semitone, returning to the original pitch (thus spanning the interval of a major second), so it is only barely audible, but it is indeed very different from the plain cluster. Here is an example: the pitch is F below middle C, the cluster is 01346, and the duration is 18 seconds. [Example 4]

To show the contrast with the previous example, the next one, which is used in the climax of the piece, goes up and down by a perfect fourth, thus covering a span of a major seventh. The pitch is C-sharp an octave and minor second above middle C, and the cluster is 01347. [Example 5]

The next instrument, which I call “sparkle” (maybe not the best description of this effect), is like the basic cluster instrument except that, instead of moving up from the fundamental, components are brought in and out in various octaves, in a pattern that leaps from one octave to the next. There is a definite order, but it is not really discernable in the context of the music, since the harmony of the clusters keeps changing. The harmony of the cluster may be clearer than in the cluster instrument, but it does not have that ascending quality of the first example. The example I have here is of the harmony 01345, and while the first five pitches that enter state those five notes in succession, the first, third and fifth are two octaves above the fundamental and the second and fourth are in the lowest octave. [Example 6]

The final instrument is one which I call a gong, although it doesn’t sound exactly like a conventional gong. It contains the pentachordal cluster within a four-octave span, but the durations of the higher notes fade away faster than the lower ones, in an even progression. These only occur in the climax of the piece, and only on a few notes. [Example 7]

Now let me talk about the composition itself, for which I have created a score that you can follow along with. There are seven sections. The score shows not only the notes, which are the notes from which the clusters spring, but also the durations along the bottom and the clusters as well, which apply to all the notes in the staves above until another one replaces it. The tempo is quarter note equals 40, and except for the beginning, cluster groups last for three measures or 18 seconds. Each section uses a group of four clusters, which are actually pentachords related under certain operations like inversion. The first three sections are based on clusters that begin with 01346, the next two are built on 01245, and the last two on 01347. Most of the piece is built on trichords. The first section is based on trichords and the second on pentachords, and the pentachords in the second section all contain the trichords from the first section, in order. The third section is also based on a different set of trichords that are extracted from the pentachords. The fourth section is all in the octave of middle C and two octaves lower, and the fifth section is based on the three octaves from middle C and above. The sixth section, the climax, spans both of these groups of registers, but stated simultaneously, and the last section uses just the octave of middle C and above. Different sections also use different groups of instruments. The first, second and last section use only the basic cluster instrument. Section 3 uses just woosh and gliss, and sections 4 and 5 use woosh, sparkle and cluster. Only section 6 uses all instruments.

The complete composition can be played here. It is available from the American Composers Alliance.

Following the completion of this piece, I have continued it into other areas. First, I wrote a similar piece in 19-tone equal temperament, called, appropriately, 19-tone Clusters. The instruments have the same basic design, but all the harmonies are in 19-tone temperament, which creates a very different kind of sound. I could not discuss this piece without giving an explanation of my approach to 19-tone harmony, so I will delay this until another time.

Then I have also written a piece for wind ensemble which has the same basic design as the electronic piece, but the clusters are put onto groups of related instruments. The basic notes shown in this score, which are the “fundamentals” of the cluster, are all played by the brasses, and all the clusters are given to the woodwinds. Wind ensemble turns out to be an excellent medium for this, because there are always lots of woodwind players. There are clusters of flutes, clarinets, saxophones, double reeds, and an extremely high group of piccolos, E-flat clarinet, and a borrowed flute or clarinet. There are also parts for string bass, piano, and pitched percussion instruments (xylophone, marimba, and chimes). The score to this piece is also available from the American Composers Alliance.