Emergent Rhythmic Structures as Cultural Phenomena Driven by Social Pressure in a Society of Artificial Agents

This thesis studies rhythm from an evolutionary computation perspective. Rhythm is the most fundamental dimension of music and can be used as a ground to describe the evolution of music. More specifically, the main goal of the thesis is to investigate how complex rhythmic structures evolve, subject to the cultural transmission between individuals in a society. The study is developed by means of computer modelling and simulations informed by evolutionary computation and artificial life (A-Life). In this process, self-organisation plays a fundamental role. The evolutionary process is steered by the evaluation of rhythmic complexity and by the exposure to rhythmic material. In this thesis, composers and musicologists will find the description of a system named A-Rhythm, which explores the emerged behaviours in a community of artificial autonomous agents that interact in a virtual environment. The interaction between the agents takes the form of imitation games. A set of necessary criteria was established for the construction of a compositional system in which cultural transmission is observed. These criteria allowed the comparison with related work in the field of evolutionary computation and music. In the development of the system, rhythmic representation is discussed. The proposed representation enabled the development of complexity and similarity based measures, and the recombination of rhythms in a creative manner. A-Rhythm produced results in the form of simulation data which were evaluated in terms of the coherence of repertoires of the agents. The data shows how rhythmic sequences are changed and sustained in the population, displaying synchronic and diachronic diversity. Finally, this tool was used as a generative mechanism for composition and several examples are presented.Leverhulme Trus

AN APPROACH TO MACHINE DEVELOPMENT OF MUSICAL ONTOGENY

This Thesis pursues three main objectives: (i) to use computational modelling to explore how music is perceived, cognitively processed and created by human beings; (ii) to explore interactive musical systems as a method to model and achieve the transmission of musical influence in artificial worlds and between humans and machines; and (iii) to experiment with artificial and alternative developmental musical routes in order to observe the evolution of musical styles. In order to achieve these objectives, this Thesis introduces a new paradigm for the design of computer interactive musical systems called the Ontomemetical Model of Music Evolution - OMME, which includes the fields of musical ontogenesis and memetlcs. OMME-based systems are designed to artificially explore the evolution of music centred on human perceptive and cognitive faculties. The potential of the OMME is illustrated with two interactive musical systems, the Rhythmic Meme Generator (RGeme) and the Interactive Musical Environments (iMe). which have been tested in a series of laboratory experiments and live performances. The introduction to the OMME is preceded by an extensive and critical overview of the state of the art computer models that explore musical creativity and interactivity, in addition to a systematic exposition of the major issues involved in the design and implementation of these systems. This Thesis also proposes innovative solutions for (i) the representation of musical streams based on perceptive features, (ii) music segmentation, (iii) a memory-based music model, (iv) the measure of distance between musical styles, and (v) an impi*ovisation-based creative model

USING INTERACTIVE SOFTWARE AS A CONCEPTUAL TOOL: AN EXAMINATION OF COGNITION IN IMPROVISED MUSICAL PERFORMANCE

Viewing musical improvisation in the light of psychology and cognitive science, this thesis will explicate the rationale behind the development of a software based audiovisual interface for use in improvised solo instrumental performance. The evolution of the performance environment is presented along with the theories and concepts that have shaped its progress. The opening chapter will review the terms of reference used throughout the work and will set a boundary around the area of examination. Chapter two will place musical improvisation within the context of human behaviour and in so doing will draw upon theoretical discourse from the fields of evolutionary psychology and cognitive science. This chapter will explore the nature of volition and its relationship with subconscious processing, drawing upon anecdotal evidence from improvising musicians as linkage between theory and practice. Chapter 3 augments the study of the inner world of the improvising musician by encompassing the communicative functions of this activity. The boundary of this study does not embrace musical interactions between musicians in a dialogic sense, my remit here is to explore behavioural response to sensory information and the mechanism by which this may or may not manifest itself in conscious thought. Chapter 4 sees the development of a theoretical model with which to contextualise the practice of musical improvisation and to provide the foundation from which to evolve the architecture for an experimental performance environment. This leads in Chapter 5 to a discussion around the function and nature of tools as problem solving devices looking at conceptual and physical tools and the mapping of functionality. The discourse in this chapter is aimed at providing a rationale for the development of a software based tool to address some of the issues raised previously in the study. The concluding chapter will document the evolution of a software based audio-visual performance environment, mapping its various incarnations and its relationship to the theoretical model developed over the course of the pervious chapters. This chapter will refer to documentation and audio visual material on CD Rom and DVD found in Appendix l

Application of Intermediate Multi-Agent Systems to Integrated Algorithmic Composition and Expressive Performance of Music

We investigate the properties of a new Multi-Agent Systems (MAS) for computer-aided composition called IPCS (pronounced “ipp-siss”) the Intermediate Performance Composition System which generates expressive performance as part of its compositional process, and produces emergent melodic structures by a novel multi-agent process. IPCS consists of a small-medium size (2 to 16) collection of agents in which each agent can perform monophonic tunes and learn monophonic tunes from other agents. Each agent has an affective state (an “artificial emotional state”) which affects how it performs the music to other agents; e.g. a “happy” agent will perform “happier” music. The agent performance not only involves compositional changes to the music, but also adds smaller changes based on expressive music performance algorithms for humanization. Every agent is initialized with a tune containing the same single note, and over the interaction period longer tunes are built through agent interaction. Agents will only learn tunes performed to them by other agents if the affective content of the tune is similar to their current affective state; learned tunes are concatenated to the end of their current tune. Each agent in the society learns its own growing tune during the interaction process. Agents develop “opinions” of other agents that perform to them, depending on how much the performing agent can help their tunes grow. These opinions affect who they interact with in the future. IPCS is not a mapping from multi-agent interaction onto musical features, but actually utilizes music for the agents to communicate emotions. In spite of the lack of explicit melodic intelligence in IPCS, the system is shown to generate non-trivial melody pitch sequences as a result of emotional communication between agents. The melodies also have a hierarchical structure based on the emergent social structure of the multi-agent system and the hierarchical structure is a result of the emerging agent social interaction structure. The interactive humanizations produce micro-timing and loudness deviations in the melody which are shown to express its hierarchical generative structure without the need for structural analysis software frequently used in computer music humanization

Live Electronic Ensemble Practice : Developing Tools and Strategies for Performance and Composition

This research is an auto-ethnographic study of a portfolio of compositions and performances in ensembles that took place across the UK and Europe between September 2008 and February 2014. This commentary analyses the work with a view to discerning useful strategies and approaches towards group work in the field of experimental electronic music. The study contains an account of the author’s own physical interface and its development over a period of ten years, including a wider analysis of some considerations for design and the development of a personal instrumental practice. Ensembles formed by the author are discussed with a focus on social psychology and self-organisation through the creation of unique roles and shifting group hierarchies, afforded by the possibilities and dislocations of technology. The commentary continues with an in-depth study of the development and performance of The Stream, a generative composition system that applies some of the interdependent behaviours and processes of self-organisation discovered through musical experimentation, to an agent-based societal model for real time score generation. The analysis shows that interdependent agents and social behaviours can be modelled in order to generate relationships which are comparable to those created through traditional methods of composition and improvisation. The study concludes that the possibilities afforded by technology to extend beyond the physical and social domain are most successfully implemented when they support, rather than inhibit the natural relationships and human physicality of those taking part. Therefore, when designing a generative composition system, the simulation of human relationships and their narratives may open up a new area of research in the generation of musical composition

Collaborating with the Behaving Machine: simple adaptive dynamical systems for generative and interactive music

Situated at the intersection of interactive computer music and generative art, this thesis is inspired by research in Artificial Life and Autonomous Robotics and applies some of the principles and methods of these fields in a practical music context. As such the project points toward a paradigm for computer music research and performance which comple- ments current mainstream approaches and develops upon existing creative applications of Artificial Life research. Many artists have adopted engineering techniques from the field of Artificial Life research as they seem to support a richer interactive experience with computers than is often achieved in digital interactive art. Moreover, the low level aspects of life which the research programme aims to model are often evident in these artistic appropriations in the form of bizarre and abstract but curiously familiar digital forms that somehow, despite their silicon make-up, appear to accord with biological convention. The initial aesthetic motivation for this project was very personal and stemmed from interests in adaptive systems and improvisation and a desire to unite the two. In sim- ple terms, I wanted to invite these synthetic critters up on stage and play with them. There has been some similar research in the musical domain, but this has focused on a very small selection of specific models and techniques which have been predominantly applied as compositional tools rather than for use in live generative music. This thesis considers the advantages of the Alife approach for contemporary computer musicians and offers specific examples of simple adaptive systems as components for both compo- sitional and performance tools. These models have been implemented in a range of generative and interactive works which are described here. These include generative sound installations, interactive instal- lations and a performance system for collaborative man-machine improvisation. Public response at exhibitions and concerts suggests that the approach taken here holds much promise

Parameter Search for Aesthetic Design and Composition

PhDThis thesis is about algorithmic creation in the arts – where an artist, designer or composer uses a formal generative process to assist in crafting forms and patterns – and approaches to finding effective input parameter values to these generative processes for aesthetic ends. Framed in three practical studies, approaches to navigating the aesthetic possibilities of generative processes in sound and visuals are presented, and strategies for eliciting the preferences of the consumers of the generated output are explored. The first study presents a musical interface that enables navigation of the possibilities of a stochastic generative process with respect to measures of subjective predictability. Through a mobile phone version of the application, aesthetic preferences are crowd-sourced. The second study presents an eye-tracking based framework for the exploration of the possibilities afforded by generative designs; the interaction between the viewers’ gaze patterns and the system engendering a fluid navigation of the state-space of the visual forms. The third study presents a crowd-sourced interactive evolutionary system, where populations of abstract colour images are shaped by thousands of preference selections from users worldwide For each study, the results of analyses eliciting the attributes of the generated outputs – and their associated parameter values – that are most preferred by the consumers/users of these systems are presented. Placed in a historical and theoretical context, a refined perspective on the complex interrelationships between generative processes, input parameters and perceived aesthetic value is presented. Contributions to knowledge include identified trends in objective aesthetic preferences in colour combinations and their arrangements, theoretical insights relating perceptual mechanisms to generative system design and analysis, strategies for effectively leveraging evolutionary computation in an empirical aesthetic context, and a novel eye-tracking based framework for the exploration of visual generative designs.Engineering and Physical Sciences Research Council (EPSRC) as part of the Doctoral Training Centre in Media and Arts Technology at Queen Mary University of London (ref: EP/G03723X/1)