Computer perception of phrase structure

A computer algorithm for modelling phrase perception in a monophonic rhythm is described and its relationship to phrase structure in general is discussed. The algorithm groups durations by proximity of attack and connections between relatively long notes, producing a hierarchy of groupings and identifying durational phrases among these. The connection between longer notes is also an aspect of metrical perception. Supplementary metrical information enables durational phrases to be read within a combined hierarchical representation of meter and phrasing, in tree-diagram form. In a wider context, structural characteristics perceptually stronger than duration, such as repetition, dissonance and resolution, and cadence, are seen to be responsible for the predominant phrase grouping when incongruent with durational phrasing. Despite the algorithm's limitations, durational phrasing provides the foundation for a broader model of phrase perception.