This is a study of the way in which digital audio and a number of key associated technologies that rely on it as a framework have changed the creation, production and dissemination of music, as witnessed by my own creative practice. The study is built on my own work as an electronic musician and composer and draws from numerous collaborations with not only other musicians but also researchers and artists, as documented through commissions, performances, academic papers and commercial releases over an 9 year period from 2007 to 2016. I begin by contextualising my own musical practice and outlining some prominent themes associated with the democratisation of computing that the work of this thesis interrogates as a critical framework for the production of musical works. I go on to assess how works using various techniques afforded by digital audio may be interpreted as progressively instantiating a digital ontology of music. In the context of this digital ontology of music I propose a method of analysis and criticism of works explicitly concerned with audio analysis and algorithmic processes based on my interpretation of the concept of `hypertext', wherein the ability for computers to analyse, index and create multi-dimensional, non-linear links between segments of digital audio is best described as hypertextual. In light of this, I contextualise the merits of this reading of music created using these affordances of digital audio through a reading of several key works of 20th century music from a hypertextual perspective, emphasising the role information theory and semiotics have to play in analyses of these works. I proffer this as the beginnings of a useful model for musical composition in the domain of digital audio which I seek to explore through my own practice. I then describe and analyse, both individually and in parallel numerous works I have undertaken that seek to interrogate the intricacies of what it means to work in the domain of digital audio with audio analysis, machine listening, algorithmic and generative computational processes and consider the ways in which aspects of this work might be seen as contributing useful and novel insights into music creation by harnessing properties intrinsic to digital audio as a medium. Finally, I emphasise, based on the music and research presented in the thesis, the extent to which digital audio and the harnessing of increasingly complex computational systems for the production and dissemination of music has changed the ontology of music production, a situation which I interpret as creating both substantial challenges, but also great possibilities for the future of music.

Ocean of Forms is a cycle of five songs for solo soprano voice and electronic/computer music accompaniment on poems by noted Bengali poet, musician, philosopher, and author Rabindranath Tagore. This work approaches the song cycle as a vehicle for expressing and highlighting the poet's words. Word and syllabic stress, text painting, melodic development, and formal structure all function in relation to the text and its meaning. the replacement of the traditional piano accompaniment with electronic accompaniment provides further possibilities for new timbral structures and transformations, expressive microtonal intonation, algorithmic and aleatoric formal structures, acousmatic and spatialized sound, and a broad sonic palette. This work strives to provide a more fully developed expression of the text as afforded by these expanded musical means. the critical essay primarily explores the interaction between text and music in the work. the first chapter explores the historical precedents for the genre of the song cycle and other texted music as well as specific influences on the work. the following chapters explore the connections between the text and the vocal line and electronic/computer music, respectively. the final chapter deals with the formal structure of the work, especially the justly-tuned harmonic scheme and its relation to the text.

Swarm robotics for music is a relatively new way to explore algorithmic composition as well as new modes of human robot interaction. This work outlines a strategy for making music with a robotic swarm constrained by acoustic sound, rhythmic music using sequencers, motion causing changes in the music, and finally human and swarm interaction. Two novel simulation programs are created in this thesis: the first is a multi-agent simulation designed to explore suitable parameters for motion to music mappings as well as parameters for real time interaction. The second is a boid-based robotic swarm simulation that adheres to the constraints established, using derived parameters from the multi-agent simulation: orientation, number of neighbors, and speed. In addition, five interaction modes are created that vary along an axis of direct and indirect forms of human control over the swarm motion. The mappings and interaction modes of the swarm robot simulation are evaluated in a user study involving music technology students. The purpose of the study is to determine the legibility of the motion to musical mappings and evaluate user preferences for the mappings and modes of interaction in problem solving and in open-ended contexts. The findings suggest that typical users of a swarm robot system do not necessarily prefer more inherently legible mappings in open-ended contexts. Users prefer direct and intermediate modes of interaction in problem solving scenarios, but favor intermediate modes of interaction in open-ended ones. The results from this study will be used in the design and development of a new swarm robotic system for music that can be used in both contexts.

A partir d'une interprétation musicologique de la notion scientifique de "modélisation et simulation'', cette thèse présente une approche d'analyse assistée par ordinateur où les partitions musicales sont reconstruites à partir de processus algorithmiques et simulées avec différents paramètres à partir desquels des variantes, appelés instances, sont générés. L'étude d'une pièce musicale par modélisation et simulation signifie comprendre l'oeuvre en la (re) composant de nouveau, en brouillant les limites entre le travail analytique et créatif. Cette approche est appliquée à trois études de cas: 1. une technique isolée, la "multiplication d'accords'', utilisé par Pierre Boulez (1925- 2016), qui a été explorée à travers le prisme formé par les théories de H. Hanson, S. Heinemann et L. Koblyakov; 2. La pièce "Spectral Canon pour Conlon Nancarrow" (1974) du compositeur américain James Tenney (1934-2006) à laquelle la simulation computationnelle à partir de différents paramètres a été prise à ses conséquences ultimes quand un "espace d'instances" est explorée a partir de stratégies de visualisation graphique; 3. Et enfin "Désordre" (1985), le première étude pour piano de l'austro-hongrois György Ligeti (1923-2006) dans laquelle les concepts de "tonalité combinatoire" et "décomposition en nombres premiers'', appliqué aux durées, ont été utilisés pour maximiser le potentiel de production d'instances. / From a musicological interpretation of the scientific notion of “modeling and simulation”, this thesis presents an approach for computer-aided analysis where musical scores are reconstructed from algorithmic processes and then simulated with different sets of parameters from which neighbouring variants, called instances, are generated. Studying a musical piece by modelling and simulation means to understand the work by (re)composing it again, blurring boundaries between analytical and creative work. This approach is applied to three case studies: an isolated technique, Pierre Boulez Chord Multiplication, which is explored through the prism formed by the theories of H. Hanson, S. Heinemann and L. Koblyakov; the piece Spectral Canon for Conlon Nancarrow (1974) by the american James Tenney (1934-2006) to which the computational simulation from different sets of parameters was taken to its ultimate consequences when a “space of instances” is created and strategies of visualisation and exploration are devised; and finally “Disorder”, the first piano study written by austro-hungarian György Ligeti in which the concepts of “combinatorial tonality” and “decomposition prime numbers”, applied to durations, are used to maximize the potential that a model has to produce different variations of the original piece.

Note sequence morphing is the combination of two note sequences to create a ‘hybrid transition’, or ‘morph’. The morph is a ‘hybrid’ in the sense that it exhibits properties of both sequences. The morph is also a ‘transition’, in that it can segue between them. An automated and interactive approach allows manipulation in realtime by users who may control the relative influence of source or target and the transition length. The techniques that were developed through this research were designed particularly for popular genres of predominantly instrumental electronic music which I will refer to collectively as Mainstream Electronic Music (MEM). The research has potential for application within contexts such as computer games, multimedia, live electronic music, interactive installations and accessible music or “music therapy”. Musical themes in computer games and multimedia can morph adaptively in response to parameters in realtime. Morphing can be used by electronic music producers as an alternative to mixing in live performance. Interactive installations and accessible music devices can utilise morphing algorithms to enable expressive control over the music through simple interface components. I have developed a software application called LEMorpheus which consists of software infrastructure for morphing and three alternative note sequence morphing algorithms: parametric morphing, probabilistic morphing and evolutionary morphing. Parametric morphing involves converting the source and target into continuous envelopes, interpolation, and converting the interpolated envelopes back into note sequences. Probabilistic morphing involves converting the source and target into probability matrices and seeding them on recent output to generate the next note. Evolutionary morphing involves iteratively mutating the source into multiple possible candidates and selecting those which are judged as more similar to the target, until the target is reached. I formally evaluated the probabilistic morphing algorithm by extracting qualitative feedback from participants in a live electronic music situation, benchmarked against a live, professional DJ. The probabilistic algorithm was competitive, being favoured particularly for long morphs. The evolutionary morphing algorithm was formally evaluated using an online questionnaire, benchmarked against a human composer/producer. For particular samples, the morphing algorithm was competitive and occasionally seen as innovative; however, the morphs created by the human composer typically received more positive feedback, due to coherent, large scale structural changes, as opposed to the forced continuity of the morphing software.