Centre for Intelligent Systems and their Applications

Musical Agents are an emerging technology, designed to provide a range of new musical opportunities to human musicians and composers. Current systems in this area lack certain features which are necessary for a high quality musician; in particular, they lack the ability to structure their output in terms of a communicative dialogue, and reason about the responses of their partners. In order to address these issues, this thesis develops Musical Act Theory (MAT). This is a novel theory, which models musical interactions between agents, allowing a dialogue oriented analysis of music, and an exploration of intention and communication in the context of musical performance. The work here can be separated into four main contributions: a specification for a Musical Middleware system, which can be implemented computationally, and allows distributed agents to collaborate on music in real-time; a computational model of musical interaction, which allows musical agents to analyse the playing of others as part of a communicative process, and formalises the workings of the Musical Middleware system; MAMA, a musical agent system which embodies this theory, and which can function in a variety of Musical Middleware applications; a pilot experiment which explores the use of MAMA and the utility of MAT under controlled conditions. It is found that the Musical Middleware architecture is computationally implementable, and allows for a system which can respond to both direct musical communi- cation and extramusical inputs, including the use of a custom-built tangible interface. MAT is found to capture certain aspects of music which are of interest — an intuitive notion of performative actions in music, and an existing model of musical interaction. Finally, the fact that a number of different levels — theory, architecture and implementation — are tied together gives a coherent model which can be applied to many computational musical situations.