Is text an adequate tool for modelling musical analysis, composition and performance?
Résumé
The Bol Processor project originated in 1980 as a word processor facilitating the transcription of quasi-onomatopoeic syllables used as an oral notation system for Indian drumming. It grew up as an expert system mimicking the ability to compose variations on a musical theme or assess their acceptability. Pattern grammars (a subset of type-2 formal grammars) proved appropriate for modelling the musical system under study. In 1989 a numeric-symbolic learning device was developed for inferring grammars from examples.
The next implementation (BP2) addressed the issue of music composition in the MIDI and Csound environments of electronic music. The new challenge was to deal with superimposed sequences of events (polyphony) within the framework of text-oriented rewriting systems. This was achieved by means of polymetric representation. Minimal descriptions of polyphonic/polyrhythmic structures may be 'expanded' by the system to produce arbitrarily complex musical scores. This 'sonemic description' is an arrangement of musical events ('sound-objects' and 'time-objects') along symbolic time measured with integer ratios.
Producing the actual performance requires additional information which the Bol Processor encapsulates in metrical/topological properties of 'sound-object prototypes'. The time-setting algorithm modifies sound-objects taking into account physical timing and their adjacent sound-objects, much in a similar way human speakers modify the articulatory parameters of speech sounds with respect to the speaking rate and influence of adjacent segments (coarticulation).
In a classical electronic music environment, musical works are represented on scores analogous to Western staff notation. Thus, human and machines rely on 'rules of interpretation' for the actual performance. The polymetric representation makes it possible to produce sophisticated time-patterns from information comprehensively imbedded in compositional rules, thereby maintaining the consistency of interpretation. This is a major discovery both for music, as 'natural' phrasing is no longer achieved by randomness. Similar frameworks could be applied to the alignment of tonal symbols in speech synthesis.
The next implementation (BP2) addressed the issue of music composition in the MIDI and Csound environments of electronic music. The new challenge was to deal with superimposed sequences of events (polyphony) within the framework of text-oriented rewriting systems. This was achieved by means of polymetric representation. Minimal descriptions of polyphonic/polyrhythmic structures may be 'expanded' by the system to produce arbitrarily complex musical scores. This 'sonemic description' is an arrangement of musical events ('sound-objects' and 'time-objects') along symbolic time measured with integer ratios.
Producing the actual performance requires additional information which the Bol Processor encapsulates in metrical/topological properties of 'sound-object prototypes'. The time-setting algorithm modifies sound-objects taking into account physical timing and their adjacent sound-objects, much in a similar way human speakers modify the articulatory parameters of speech sounds with respect to the speaking rate and influence of adjacent segments (coarticulation).
In a classical electronic music environment, musical works are represented on scores analogous to Western staff notation. Thus, human and machines rely on 'rules of interpretation' for the actual performance. The polymetric representation makes it possible to produce sophisticated time-patterns from information comprehensively imbedded in compositional rules, thereby maintaining the consistency of interpretation. This is a major discovery both for music, as 'natural' phrasing is no longer achieved by randomness. Similar frameworks could be applied to the alignment of tonal symbols in speech synthesis.