Creative performances may be seen as a dynamic contact point between the preconceived expectations from the performers, musicians, and audience. There exists a potential tension between composer control and trust in the performers, particularly when improvised musical elements occur alongside pre-composed material. Undetermined elements within the score can have significant impact on the performance of a composition through the interpretation of the musicians. As an active composer and performer, I find this tension between control, trust, and interpretation fascinating.

This thesis investigates the relationship between composition, improvisation, and performance within my own artistic practice. It traces the process of composing, performing, and recording new music for four ensemble projects, each of which opens different modes of practice and ways of weaving together fixed and open-ended aspects of music. These new compositions were designed to explore the interaction between the score and the performer through integrating improvisation to varying degrees, using what I call unfixed elements.

At play throughout the dissertation are theoretical concepts of ecological systems and the process of making to provide context and terminology and to help tease out the sonic and temporal interplay of composition and improvisation. The central research question is: In what ways are improvisation, composition, and performance related and realised within my artistic practice? This question is addressed through the three sub-questions. First, what are the roles of unfixed elements within my new compositions? Second, how is compositional intention conveyed? Third, what can be learnt about the tension between control and trust in composition if we view performance as an ecological system and a process of making?

There are three key contributions to new knowledge from this research study. First, a body of original compositions and recordings has been created and presents the artistic representation of the research. Second, placing this output, along with the accompanying reflection on the process, within a conceptual framework of making and ecological systems offers a perspective on how improvisation, composition, and performance can relate. And third, the study offers practical insight and tools for effectively integrating unfixed elements within ensembles featuring western classical and improvising musicians. A core feature across all three contributions is the emphasis that they place on the interaction and process of performance. As this research is multidimensional, the new knowledge that has been generated is applicable to a diversity of fields, including composition, improvisation, and performance.