Hierarchical perception of melody

Abstract

Two experiments were designed to investigate the hierarchical perception of melodies. The hierarchical structure of tonal melodies is formally described in Lerdahl and Jackendoff's Generative Theory of Tonal Music (GTTM). The experiments were designed to assess different aspects of GTTM time span reduction quantitatively. Subjects were presented with pairs of melodies in a same-different task. A short novel and a longer original tonal melody could differ within the harmonic context at single tones on one of four time span reduction levels. It was found that detection rate of the melodic deviances correlated strongly with time span level. The same method was employed on an atonal and a poorly composed tonal melody. Detection rates were lower for the atonal but not for the ill-formed melody, and responses still varied significantly with position of the deviant tone. Generally, the correlation of responses with reductional level was found to be much stronger than with alternative musical parameters that could be thought to influence detection rate, such as metrical position. The obtained quantitative measures of hierarchical levels suggest that these are subject to variations not normally envisaged by music analysis. It is suggested that hierarchical levels may be graded in nature, with the perceived hierarchical depth depending on the nature of the melodic sequence.