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Vanessa Hawes

Dynamic probability and ecological perception: musical information in retrospect and anticipation (10/06/10)

The theoretical basis for the system of computational analysis explored here is a dynamic probability model of musical perception first proposed by Coons and Kraehenbuehl in 1958. The method models an ideal listener's experience of a sequence of musical events, as he adapts his expectations throughout the experience of a specific sequence. The output of the system is a series of percentages representing relative information for each event in a sequence (relative to the maximum information measure possible). Importantly, the musical sequences and events forming the basis for the analysis are consciously chosen by a particular analyst and can be defined in the terms of his particular point of view specific music; a point of view characterized by his level of familiarity with the music and/or by his music theoretical experience and beliefs. The particular musical features taken into account for the decisions of the system are also a pre-analytical decision and can vary depending on the analyst. The results produced by the analysis, then, represent something of the relationship between the analyst and the music. The original method is outlined and problems specific to its application to real music, such as the absence of the effect of long-term memory in the model, are addressed with recourse to ecological approaches to musical perception. The system is used for an examination of various pieces of music, with particular attention paid to the analysis of themes in terms of notes (pitches, durations, intervals). Bach's BWV 1030b forms the bulk of the analysis, with particular attention paid to its six themes. Various structural groupings defined by an analyst are interpreted into information profiles. These results are contextualized with recourse to contemporary music theoretical discourse, and the possibility of using this method to illustrate features of particular analytical methodologies is explored. The presentation is part of a continuing collaborative project, 'Scalable Analytical Approaches and Performative Affordance', the first outcome of which will be a symposium for the International Conference of Music Perception and Cognition in Seattle in August 2010.