ARTICULATED NOISE
Eric Lyon
Sonic Arts Research Centre
School of Music & Sonic Arts
Queen’s University Belfast
e.lyon@qub.ac.uk
ABSTRACT
Articulated noise is a computer-assisted strategy for
applying various flavors of noise to the structuring of
musical compositions. The approach applies equally
well to creating electroacoustic music and instrumental
scores, and makes no assumptions about musical style.
Articulated noise is discussed here in terms of its
precedents, philosophical and aesthetic basis, methods
adopted by the author, and current compositional work
employing the approach.
1.
ORIGIN OF ARTICULATED NOISE
The impetus for articulated noise emerged from “Rose
of the World,” a work of computer music I composed
for the CD “Clairaudience: New Music from Electronic
Voice Phenomena (EVP)” [4]. EVP is a scientifically
unverified method of allegedly detecting spirit voices
captured on blank media such as magnetic tape. Absent
confirmation of supernatural causation, EVP may be
regarded as an example of a statistical “type I error,” a
false positive. My compositional approach in “Rose of
the World” was to mix an EVP recording into a
synthetic noise texture, thus reversing the process: a
sound extracted from analog noise was re-inscribed into
digital noise. Patterns perceived in, or imposed upon
noise emerged as a primary aesthetic goal.
2.
AUDIO EXPERIMENTS
My first experiments with articulated noise were
inspired in part by a noise unit generator found in a
popular acoustic compiler that used a poor-quality
pseudo-random number generator (PRNG) with a short
period before repetition. The result of using this unit
generator was to hear noise that repeated an audible
rhythmic pattern, due to the short periodicity of the
PRNG. I experimented with laying noise looped in
different periodicities, and found that when the layers
are separated spatially, the repetition patterns are quite
easy to hear. When the period lengths are lowered to the
audible frequency range, a clear, but somewhat rough
pitch is perceived. Tones generated this way can be
banked into chords. This kind of looped noise is similar
to the Karplus-Strong algorithm [3] but lacking the
feedback and lowpass filter element. One important
difference to Karplus-Strong is that the noise contents
become more important to the resulting sound. In
Karplus-Strong, the effects of feedback and filtering
soon overcome the specific attributes of the triggering
noise burst. However in looped noise tones, the timbre
is significantly determined by the noise content, since
the noise segment is treated as a waveform. The
interaction of looped noise segments, spatial
articulation, and various levels of structural articulation
remains an ongoing research project feeding current
compositional work-in-progress.
3.
POST-COHERENT MUSIC
The experiments with audio noise at various time scales
led me to consider the application of noise to the
articulation of musical constructs appropriate to
expression in traditional score form. Of course
generating scores algorithmically is a relatively old
practice, and precedents are discussed below. But the
emphasis here is to give noise as much influence on the
music at all levels as possible, just short of having the
music itself sound “random.” The intention is to foster
“type I error” listening in both electroacoustic and
instrumental music. This kind of music and listening
engages a long-standing concern with what I now call
“post-coherent” music. A discussion of post-coherent
music requires a discussion of musical coherence, which
is well beyond the scope of this paper. However I will
propose as a baseline notion that the coherence of a
musical work is inversely proportional to how robustly
it can survive having its elements randomly reordered.
Coherence can be maintained in electroacoustic
music by limiting the sonic vocabulary of any particular
piece and drawing on a relatively predictable gestural
syntax, such as is often present in acousmatic music.
But a post-coherent approach takes advantage of the
lack of performance cues inherent in electroacoustic
music, along with the computer-based ability to easily
store and catalogue huge varieties of sound, to pursue
surprise, non-linearity, and incongruous juxtapositions,
at the risk of losing touch with traditional musical
notions of coherence.
3.1 Beyond 20th Century Coherence
Post-coherent music could be considered a reaction to
late 20th century modes of information perception,
notably a nonlinear information overload resulting from
exposure to increasingly rapid push media with
conflicting ideological messages, as well as the basic
mode of information traversal on the Web itself. I’d
further suggest that an extreme view of musical
coherence is itself a 20th century ideology, promoted by
two of the most important European art music theorists
of that century: Heinrich Schenker and Arnold
Schoenberg. Schenker’s model of tonal music [8]
promotes a hierarchical view of levels, each following
similar rules of good construction based largely on J. J.
Fux’s rules of species counterpoint [2] and on a
rejection of J. P. Rameau’s chord-based theory of
harmony [7]. Ultimately, extended tonal pieces are seen
as ramified expressions of a simple contrapuntal
framework that expresses a single tonality, thus viewing
tonal compositions as coherent, organic unities. As
Schenker states in the introduction to his summative
work “Free Compostion,” “I present here a new concept,
one inherent in the works of the great masters; indeed, it
is the very secret and source of their being: the concept
of organic coherence. [7]” Schoenberg’s “method of
composing with twelve notes which are related only to
one another other” is a compositional attempt to achieve
post-tonal coherence, by defining a single structure, the
tone row, as the source of all musical material for an
entire composition according to the principles of
motivic and set-based transformation. In his essay
“Twelve-Tone Composition” Schoenberg asserts, “the
main advantage of this method of composing with
twelve tones is its unifying effect” [9]. Whether the
ideas of Schenker and Schoenberg constitute timeless,
universal insights into the art of musical composition (as
the tone of their writings often suggests) or rather a
localized product of the historical and political climate
in which they were formed remains an open question.
3.2 A 1990s Example of Post-Coherent Music
In the realm of computer music, Christopher Penrose’s
work is an important representative of post-coherent
strategies. One finds in early Penrose works from the
1990s such as “Fraud” [5] an overwhelming amount of
sonic material, and audio processing strategies. The
music is more concerned with how to move from one
distinctive sound to another than with defining a
coherent sound world. However coherence can be
established not just by interrelated materials, but also by
form, and “Fraud” does indeed have an extremely clear
and well-articulated large-scale form over its 27-minute
duration. In later works, starting from “Manwich” [6]
formal coherence is abandoned and fluid forms are
embraced in which any potential event no matter how
seemingly unrelated to what came before, can be
accommodated into the musical structure.
4.
SCORED NOISE ARTICULATION
The technique of articulated noise applied to
instrumental music uses noise to make musical
decisions at most levels of a composition. However
composer design is fully engaged at two crucial levels.
First, the composer designs templates – musical
structures that can be combined to provide a set of
constraint specifications at any point in the piece. One
template might describe pitch constraints, which might
result in a specification of an unordered pc-set, a series
of randomly chosen pitches, a single pitch, the absence
of pitch material (requiring either silence or “noisy”
non-pitched articulation), or even a specification to the
composer to invent local pitch materials. Other
templates might affect meter, rhythm, tempo, dynamics,
articulation and so forth. The second composer
intervention is at the surface level of composing. The
intersection of noise-driven templates results in a
specification set, sometimes extremely constrained, that
still allows some degree of compositional discretion.
Thus the composer fully crafts the surface of the piece
within constraints that were also composer-determined,
but randomly applied. Two important results obtain
from applying this technique. First, at whatever
granularity that is selected, there is no guaranteed
correlation from one grain to the next. This frees the
composer to focus completely on the crafting of single
grains, without concern for how they relate to other
grains in the piece. Second, the intersection of random
decisions and selections of multiple templates results in
combinations that the composer is unlikely to have
selected if working purely by intuition. In extreme cases
this may result in musical surfaces that are physically
impossible to perform at the specified tempo. The result
of this technique is a carefully crafted musical skin,
painted upon a structure that is noisy at every other
level, inviting “type I error” hearing below the surface.
4.1 Types of Noise Employed
In my recent uses of the technique, I have employed
white noise, grey noise, and pink noise, all from PRNGs
in SuperCollider. But the noise source could come from
anywhere, including digitized natural sources of noise
such as solar noise.
5.
THREE ARTICULATED NOISE
COMPOSITIONS
My completed instrumental articulated noise
compositions are for relatively small forces: two duos
one solo piece, and most recently a song cycle for
mezzo-soprano and small mixed ensemble. Noise is
often associated with mass, and I wished to use noise to
generate much more delicate surfaces. My “Three
Noises for Violin and Piano” explore different degrees
of de-correlation between the two parts. In the first
movement, “White,” the violin and piano parts are
almost completely uncorrelated, as each has its own
complete set of unrelated templates. The one exception
is that one of the piano templates calls for the piano to
double the violin, so at certain moments the two
instruments play the same materials. In the second
movement, “Pink” there is a high degree of correlation
as piano chords provide pitch materials for violin
harmonic melodies. The final movement, “White” is a
toccata-like piece where the piano exclusively hammers
chords on noise-generated rhythms while the violin
follows various melodic templates. Although violin and
piano follow different templates, the complimentary
nature of the templates invites a unified hearing of the
two instrumental parts of this movement.
5.1 White and Grey
My flute duo “White and Grey” employs white noise
and grey noise. The two parts vary in pitch correlation
from no correlation to similar or identical pitch
materials. Modes of articulation often vary between the
two parts. Any particular bar might find the two flutes
cooperating, conflicting, or one of the flutes taking a
solo. Noise driven tempo changes often result in sudden
shifts of musical character. Use of two flutes creates
potentially heterogeneous textures, but requested spatial
separation on stage in performance invites segregated
hearing as well.
5.2 Piccolo Noise
This piccolo solo is based on white noise. Its rhythms
are much simpler than my other two works discussed
here, as the templates organize a stream of exclusively
16th notes at a fixed tempo of mm 115. Most of the
patterning is in pitch, dynamic patterns that encompass
several bars, and rhythmic modes. The result of this is a
rather light piece, which feels almost as if it could have
been composed without the use of noise. However
certain surprising breaks to the texture suggest
otherwise.
6.
PRECEDENTS - XENAKIS
There are many precedents for this work in the history
of both instrumental and computer music composition. I
will discuss three of the most prominent. The most
direct precedent is the work of Iannis Xenakis, both in
his writings, notably Formalized Music, and in his
compositional practice of stochastic music [10]. There
are however differences to Xenakis’ practice. Xenakis
was often concerned with noise as mass, whether from
nature (rain drops) or mass movements of people. The
noise as mass is shaped by sieves or generated
according to desired density patterns. Mass textures are
not a specific concern of articulated noise, but rather
belong in the domain of algorithmic composition.
Xenakis very carefully organized his musical structures,
from an aesthetic standpoint, particularly at the larger
level of form. Xenakis did indeed generate formal
structures stochastically, but he would moderate the
results if they were not in keeping with his musical
intentions. In articulated noise, larger structural
determinants are noise driven, including matters as
fundamental as overall duration. In general
compositional intervention is avoided except at the
surface level of the music.
6.1 Cage and Indeterminacy
Another important precedent is John Cage’s work with
indeterminacy [1]. Like Cage, I am using random
procedures to bring about musical results that would not
have come about from intuitive methods. But Cage uses
indeterminacy procedures in an attempt to free himself
from his own preferences. I embrace my preferences,
and use them as a guide to creating the music I want to
hear. Articulated noise is simply another compositional
strategy for exercising my preferences. A different
composer using an articulated noise approach will arrive
at very different sounding music than I do.
6.2 Ferneyhough and New Complexity
Like some outcomes from articulated noise, Brian
Ferneyhough’s music is often impossible to play as
notated. However in Ferneyhough’s music, every
individual moment is playable, and generally quite
idiomatic to the instrument as well. It is the
accumulation of concentrated musical information over
time that overloads the performer’s processing
capabilities resulting in performance failure, an
anticipated outcome for this music. The intent is for the
performer to try as hard as possible to perform the work
accurately even while knowing that some degree of
failure is unavoidable. This generates considerable
performance excitement in Ferneyhough’s music. The
impossible passages that result from articulated noise
procedures have a different meaning. They occur, if at
all, as an artefact of allowing the intersection of
templates to generate extreme behaviors. They could be
filtered out if desired, so that the decision to leave an
impossible moment in a score becomes an aesthetic
decision for the composer. And its presence in the score
becomes just another interpretive challenge for the
performer (see Figure 1). In a new complexity
composition, the performer cannot predict when he or
she will become overwhelmed in the performance. By
contrast impossible moments in articulated noise
compositions tend to be isolated, and thus can be
identified and prepared for in advance of performance.
7.
FUTURE WORK
I have recently completed a song cycle for mezzosoprano and small chamber ensemble on two Dutch
poems by Samuel Vriezen, commissioned for this piece.
By agreement with the poet, the meaning of the poems
was not revealed to me until after the text had been set.
Noise drove such aspects as vocal-emotive expression
on a per-word basis, orchestration, and large-scale
harmonic schemes. Early reports from rehearsals
indicate that the experiment was successful. I now plan
to write articulated noise compositions for much larger
ensembles. I am also working on a multi-channel
electroacoustic articulated noise piece using as its
primary source material audio frequency waves detected
in Jupiter’s magnetosphere. In the electroacoustic genre,
noise procedures are useful for specifying processing
schemes, panning schemes, and parameters. It is
possible to use the sound source itself as a source for
random numbers.
8.
CONCLUSIONS
Articulated noise is a compositional strategy with great
flexibility that delivers structural randomness while
leaving plenty of room for individual surface-level
compositional expression. The approach as described
here is closely tied to a post-coherent musical aesthetic.
However such linkage is not inherent in the method.
Indeed my articulated noise compositions may well
sound more coherent to some listeners than some of my
music composed with more traditional strategies. But
articulated noise is a strategy of destabilization. It
invites composers to be guided by noise to the
maximum possible extent, while still affording us the
luxury of shaping the results at the tail end of the
process.
Figure 1. Excerpt from “Three
Noises for Violin and Piano,” movement 1,
“White.”
9.
REFERENCES
[1] Cage, J. Silence: Lectures and Writings.
Wesleyan University Press, Hanover, 1961,
1973.
[2] Fux, J. (Trans. and Ed. Mann, A.) Gradus Ad
Parnassum. W.W. Norton & Co., New York,
1725, 1965.
[3] Karplus, K., Strong, A. “Digital Synthesis of
Plucked String and Drum Timbres”, Computer
Music Journal. 7(2): 43-55, 1983.
[4] Lyon, E. “Rose of the World” on
Clairaudience: New Music from Electronic
Voice Phenomena. Bohn Media, BMC001,
Boston, 2006.
[5] Penrose, C. “Fraud”, on After the Taj Mahal.
Mindfall Recordings, San Diego, 1992, 1996.
[6] Penrose, C. “Manwich”, on After the Taj
Mahal. Mindfall Recordings, San Diego, 1993,
1996.
[7] Rameau, J.P. (Trans. Gossett, P.) Treatise on
Harmony. Dover Press, New York, 1726, 1971.
[8] Schenker, H. (Trans. and Ed. Oster, E.) Free
Composition. Longman Inc., New York, 1935,
1979.
[9] Schoenberg, A. (Trans. Black, L. and Newlin,
D.), Style and Idea. St. Martins Press, New
York, 1950, 1975.
[10] Xenakis, I. Formalized Music: Thought and
Mathematics in Composition. Pendragon Press,
New York. 1971, 2001.