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Cognitive Constraints On Compositional SystemsFred Lerdahl's "Cognitive Constraints on Compositional Systems" cites Pierre Boulez's Le Marteau sans Matre (1954) as an example of "a huge gap between compositional system and cognized result," though he "could have illustrated just as well with works by Milton Babbitt, Elliott Carter, Luigi Nono, Karlheinz Stockhausen, or Iannis Xenakis". In semiological terminology this may be called gap between the poeitic and esthesic processes. To explain, and eventually to help end, this Lerdahl proposes the concepts of musical grammars, "a limited set of rules that can generate indefinitely large sets of musical events and/or their structural descriptions." He further divides this into compositional grammar and listening grammar, the latter being "more or less unconsciously employed by auditors, that generates mental representations of the music". He divides the former into natural and artificial compositional grammars. While the two are historically and fruitfully mixed freely, a natural grammar arises spontaneously in a culture while an artificial one is a conscious invention of an individual or group in a culture and the "gap" may only exist between listening grammar and artificial grammars. To begin to understand the listening grammar Lerdahl and Ray Jackendoff created a theory of musical cognition, A Generative Theory of Tonal Music (1983) ISBN 026262107X. This theory is outlined in the essay, and constraints on artificial compositional grammars are quoted below: Constraints on event sequences - Constraint 1: The musical surface must be capable of being parsed into a sequence of discrete events.
- Constraint 2: The musical surface must be available for hierarchical structuring by the listening grammar.
- Constraint 3: The establishment of local grouping boundaries requires the presence of salient distinctive transitions at the musical surface.
- Constraint 4: Projections of groups, especially at larger levels, depends on symmetry and on the establishment of musical parallelisms.
- Constraint 5: The establishment of a metrical structure requires a degree of regularity in the placement of phenomenal accents.
- Constraint 6: A complex time-span segmentation depends on the projection of complex grouping and metrical structures.
- Constraint 7: The projection of a time-span tree depends on a complex time-span segmentation in conjunction with a set of stability conditions.
- Constraint 8: The projection of a prolongational tree depends on a corresponding time-span tree in conjunction with a set of stability conditions.
Constraints on underlying materials - Constraint 9: Stability conditions must operate on a fixed collection of elements.
- Constraint 10: Intervals between elements of a collection arranged along a scale should fall within a certain range of magnitude.
- Constraint 11: A pitch collection should recur at the octave to produce pitch classes.
- Constraint 12: There must be a strong psychoacoustical basis for stability conditions. For pitch collections, this entails intervals that proceed gradually from very small to comparatively large frequency ratios.
- Constraint 13: Division of the octave into equal parts facilitates transposition and reduces memory load.
- Constraint 14: Assume pitch sets of n-fold equal divisions of the octave. Then subsets that satisfy uniqueness, coherence, and simplicity will facilitate location within the overall pitch space.
Pitch Space - Constraint 15: Any but the most primitive stability conditions must be susceptible to multidimensional representation, where spatial distance correlates with cognitive distance.
- Constraint 16: Levels of pitch space must be sufficiently available from musical surfaces to be internalized.
- Constraint 17: A reductionally organized pitch space is needed to express the steps and skips by which cognitive distance is measured and to express degrees of melodic completeness.
He concludes, "Some of these constraints seem to me binding, other optional. Constraints 9-12 are essential for the very existence of stability conditions. Constraints 13-17, on the other hand, can be variously jettisoned." Examples given are South Indian music which doesn't modulate and isn't equally tempered (13 & 14) and music such as that of Claude Debussy, Bla Bartk, and others which "have developed consonance-dissonance patterns directly from the total chromatic." (14-17) Comprehensibility and value - Aesthetic Claim 1: The best music utilizes the full potential of our cognitive resources.
- Aesthetic Claim 2: The best music arises from an alliance of a compositional grammar with the listening grammar.
To these ends he proposes the use of the terms "complexity" and "complicatedness", complexity positively being hierarchical structural richness, and complicatedness neutrally being musical surfaces which contain "numerous non-redundant events per unit time...All sorts of music satisfy these criteria - for example, Indian raga, Japanese koto, jazz, and most Western art music. Rock music fails on grounds of insufficient complexity. Much contemporary music pursues complicatedness as compensation for a lack of complexity. In short, these criteria allow for infinite variety but only along certain lines." "I find this conclusion both exciting and - initially at least - alarming...the constraints are tighter than I bargained for." "My second aesthetic claim in effect rejects this 'progressivist' attitude in favour of the older view that music-making should be based on 'nature'. For the ancients, nature may have resided in the music of the spheres, but for us it lies in the musical mind." Source *Lerdahl, Fred (1992). Cognitive Constraints on Compositional Systems, Contemporary Music Review 6 (2), pp. 97-121.
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