Information Representation for Analysis and Interpretation of Motivic Order

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 draws on a listener’s experience of a sequence of events, as he adapts his expectations in the light of what has happened in the sequence up to that point. The output of the system is a series of percentages representing relative information for each event in a sequence.

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 Bach’s BWV 1030b, where various structural groupings defined by the analyst are interpreted into information profiles. Particular attention is paid to differences in information profiles for sequences where identifiable motives are ordered differently. The event sequences within those motives are then examined and characteristic information profiles for each motif are produced.

These results are presented as examples of performative affordance, and the future development of tools for practical music making based on the analysis described is suggested