Improvisation: methods and models Part III. A Model of improvisation

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Improvisation methods and
models Part III. A Model of improvisation
ISE575c/CSCI575c/EE675c Topics in Engineering
Approaches to Music Cognition Human-Centered
Computing in Generating Music

• Author Jeff Pressing
• Reviewer ChangHyun Kim
• Date 2007. April. 19th.

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Index

• How people improvise
• The development of improvisational skill
• Conclusion

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How people improvise ?

• Event Cluster, Ei
• Sections containing a number of musical events
• Improvisation I E1, E2, , En
• (E, R, G, M)I -gt Ei1 Solo mode
• R the referent
• G a set of current goal
• M a long term memory
• (E, C, R, G, M)ik -gt Eik1 Ensemble mode
• Subscript k 1,K, K members of an improvisation
  ensemble
• C performer ks cognitive representation of all
  previous event clusters produced by the other
  performers and any expectations of their likely
  future actions
• For simplicity, this paper only deals with Solo
  mode.

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Event Cluster in aspects viewpoint

• Having a number of simultaneously valid and
  partially redundant aspects
• Acoustic aspect
• Produced and sensed sound
• Musical aspect
• Cognitive representation of the sounds in terms
  of music-technical and expressive dimensions)
• Movement aspect
• Timing of muscular actions, proprioception,
  touch, spatial perception, and central monitoring
  of efference
• What else? Visual and Emotional aspects, etc

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Event Cluster in forms viewpoint

• Each event clusters have intended and actual
  forms.
• Definition of Ei an event happened during time
  point ii1
• Intended form of Ei Specified in specific time
  point i by the previous events time point from 1
  to i-1.
• Actual form of Ei Constructed from subsequent
  sensory feedback from time point i to the right
  before i1.
• The gap between these two forms is reduced by
  sound training in musicianship and improvisation
  practice, but it never dwindles completely to
  zero.

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Details of the proposed model of what occurs in
the (i1)th situations

• Ei is triggered and excuted
• Each aspect of Ei may be decomposed into three
  types of analytical representation objects,
  features, and processes.
• Objects correspond to a chord, a sound, or a
  certain finger motion.
• Features are parameters that describe shared
  properties of objects.
• Processes are descriptions of changes of objects
  or features over time.

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Continued(1)

• 3) The structures of the three types of arrays
• ..\SCANNINGS\SCANNINGS\Modified\Figure1.JPG
• 4) Production of Ei1 occurs primarily on the
  basis of long-term factors(R, G, STYLISTIC NORMS,
  AND ONGOING PROCESSES)
• Two methods of continuation Associative or
  interrupt generation

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Continued(2)

• Associative and Interrupt generation
• Associative generation
• Based on either similarity or contrast.
• On the similarity type generation basis,
  significant object array components behave
  analogously, (vjk)ti (vjk)ti1
• On the contrast type generation basis, at least
  one strong component of either the feature or
  process arrays must either move from near one end
  of its possible range of values to near the
  opposite end, or cross some perceptually
  significant boundary.
• Examples When a group of high notes is followed
  by a group of low notes, or an accelerando
  changes of decelerando, or bright timbres are
  replaced by dull timbres.
• Interrupt generation
• Based on the resetting of all or a significant
  number of the strong array components without
  regard to their values in the current event
  cluster Ei.
• Capable to single out the common event clusters,
  which have nearer (O,F,P) points on the 3D OFP
  axises, We call this common event clusters as
  Event Cluster class, K. ..\SCANNINGS\SCANNINGS\M
  odified\Figure2.JPG
• Now, we can redefine improvisation I K1, K2,
  , KA
• If Ka Kb, we call it recursion in formal
  design of the improvisation.

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Continued(3)

• The choice between association and interrupt
  generation ..\SCANNINGS\SCANNINGS\Modified\Figure3
  .JPG
• may be formally modeled by the comparison between
  a time-dependent tolerance level for repetition,
  L(t) and the degree of current repetition, Z(t).
• In case Z(t) L(t), an interrupt generation
  happens, so that Z(t) jumps to a low value.
• Otherwise, associative generation continues.

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Continued(4)-Last sequence

• 5) Finally, once Oi1, Fi1, and Pi1 are
  selected for all relevant aspects, tunable
  cognitive and motor programs are set in motion
  that generate, on the basis of these higher
  constraints and current motor positions, a
  specific action design. At this point we have
  reached ti1 and this loop of the process
  (Ei-gtEi1) is complete. By iteration, then, the
  entire improvisation is built up.
• Author said that hierachically and
  sytemacitically repetitive model of event
  clusters, aspects and O,F,P is the most effective
  strategy for improvisation as Figure 7.4 shows.
• ..\SCANNINGS\SCANNINGS\Modified\Figure4.JPG

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How are Objects, Features, and Processes made?

• In Ecological perspective
• Neurologically innate, but that they are only
  brought into being by interaction with the
  environment
• Objects are inferred to exist on the basis of
  perceived invariance in sensory input over time,
  and boundedness in a space(whether physical,
  musical, or abstract)
• Features are tunable parameters and come to be
  abstracted on the basis of perceived similarity
  or contrast in sensory input.
• Processes come about from perceived change in an
  object or along a feature dimension with time.
• Over the course of ones life new arrays and
  array components are constantly being created by
  new perceptions and new perceptual groupings.

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Two improvisation examples

• First, Examples of continuation of an event
  cluster under the emphasis of selected array
  components
• Emphasis give to a particular component means
  that it will guide the generation of subsequent
  events.
• Continuation model from 1-8 exemplify associative
  continuation, with 7 and 8 more abstract than the
  others.
• While number 9 is interrupt based.
• ..\SCANNINGS\SCANNINGS\Modified\Figure5.JPG

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Two improvisation examples

• Second Example is a continuation of an event
  cluster under the description.
• Continuations 1 and 2 are of associative type,
  whereas 3,4, and 5 are interrupt type.
• Notice that here description emphasizes the motor
  aspect, since there is no extensive tradition of
  music theory which applies to such a sound
  source.
• ..\SCANNINGS\SCANNINGS\Modified\Figure6.JPG

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How are the residual decisions in improvisation
made?

• What is the residual decision in improvisation?
• For example, the choice of array components
  that will be singled out to act as strong
  constraints or to be reset.
• The answer has no philosophical agreement,
  because it is quite subjective such as the
  definition of the creativity last lecture from
  BeomSoo Kim. So I can say Different from person
  to person.
• Intuition follow the naturally correct fashion.
• Free will Unique conscious entity.
  Transpersonal.
• Physicalist Illusory or simply a somewhat
  misleading metaphor for certain complex
  characteristics of the system.
• Randomness As the improviser becomes more and
  more expert through practice and more and more
  control proceduers are built up, random processes
  need to be invoked less and less frequently and
  overall error levels decrease, perhaps
  approaching a minimum threshold.
• According to authors testing apparatus(modified
  midi synthesizer input software), the intuition
  and random perspectivess effect on improvisation
  can be determinable, but not yet performed.
  Meanwhile, the other two perspectives of
  physicalist and free-will does not determinable
  how much influence while the improviser decide
  the residual problems. No experiment have been
  designed for these two factors.

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The development of improvisational skill

• What kind of improvisation skills are there?
• Improved efficiency, fluency, flexibility,
  capacity for error correction, and, less
  universally expressiveness.
• Two additionals the inventiveness and the
  achievement of coherence
• What methods are needed for improving the
  improvisation skills?
• 1)Increase in the memory store of objects,
  features, and processes in musical, acoustic,
  motor (and other) aspects
• 2)Increase in accessibility of this memory store
  due to the build-up of redundant relationships
  between its constituents and the aggregation of
  these constituents into larger cognitive
  assemblies
• 3)Increasingly refined attunement to subtle and
  contextually relevant perceptual information

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Conclusions

• This chapter covers the process of musical
  improvisation by first examining the modeling
  tools available from a number of different
  disciplines.
• A cognitive model has then been presented for the
  process itself, followed by a brief discussion of
  its relation to improvisational skill
  acquisition.
• In this cognitive model, there are redundant
  aspects(acoustic, musical, movement, etc.), each
  of these into types of analytical
  representation(objects, features, processes), and
  each of these into characterizing elements(array
  components).
• Also this model have synergistic and capable of
  behavioural novelty, due to the extensive
  redundancy of the cognitive representations and
  the distributed and non-linear character of the
  outlined control processses.
• The fundamental nature of the improvisation
  process is considered to be the stringing
  together of a series of event clusters during
  each of which a continuation is chosen, based
  upon either the continuing of some existing
  stream of musical development(called here an
  event-cluster class)by association of array
  entries, or the interruption of that stream by
  the choosing of a new set of array entries that
  act as constraints in the generation of a new
  stream(new event-cluster class).
• There are four decision making criteria, such as
  intuition, free will, physical causation, and
  randomness.