Musical rhythm: A formal model for determining local boundaries, accents and metre in a melodic surface

Abstract

In this paper a general theory will be introduced that allows the description of a melodic surface - i.e. a score-like representation of a melody - in terms of local grouping, accentuation and metrical structures. Firstly, a formal model will be proposed that detects points of maximum local change that allow a listener to identify local perceptual boundaries in a melodic surface. The Local Boundary Detection Model (LBDM) is based on rules that are relating to the Gestalt principles of proximity and similarity. Then, it will be shown that the accentuation structure of a melody may automatically be inferred from the local boundary grouping structure. This is based on the assumption that the phenomenal accents of two contiguous musical events are closely related to the degree by which a local boundary is likely to be perceived between them. Finally, the metrical structure is revealed by matching a hierarchical metrical template onto the accentuation structure. It is suggested that the Local Boundary Detection Model presents a more effective method for low-level segmentation in relation to other existing models and it may be incorporated as a supplementary module to more general grouping structure theories. The rhythmic analyses obtained by the methods described herein are tentative, and complementary to higher-level organizational theories.