Improvisation and compressibility as complementary methods of generating and controlling musical material in notated composition

  • Stephen Coyle

Student thesis: Doctoral ThesisDoctor of Philosophy


The works included in this portfolio are linked by their exploration of two specific concepts, namely the use of improvisation as a part of the composition process, and the use of a concept termed compressibility to moderate the creation and development of musical materials.

Improvisation, carried out exclusively by the composer, is used as a core practice throughout the composition process. In other words, it is used both to generate raw material, and to develop and refine this material into fixed and fully-notated compositions.

The works of this portfolio explore this process in relation to pieces ranging from short solos to large-scale ensemble compositions. Compressibility relates to a specific assessment of material, whether improvised or not, which considers its information content and rate of change along harmonic and rhythmic axes. This assessment is used to guide the harmonic and rhythmic direction of a composition, both during the above improvisatory processes and during the process of composing in general.

This text is divided into three main chapters: the first sets out the specific details of the improvisation-based composition methods used; the second defines and explains the concept of compressibility; the third then presents a specific commentary on each piece of the portfolio. Below is a list of the works of the portfolio, followed by an index of recordings. Where a recording is not available, a computer-generated realisation of the piece is instead included.
Date of AwardDec 2019
Original languageEnglish
Awarding Institution
  • Queen's University Belfast
SponsorsNorthern Ireland Department for the Economy
SupervisorPiers Hellawell (Supervisor) & Simon Mawhinney (Supervisor)


  • compressibility
  • improvisation
  • information density
  • computer-aided performance
  • multi-tempo

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