Below is an overview of some of the theses researched at SARC
A Portfolio of Original Compositions using a Physically Inspired Sound Synthesis Approach
Supervisors: Paul Wilson, Maarten van Walstijn
This thesis accompanies a portfolio of compositions and, in addition, discusses a number of compositional approaches which make use of physical modelling and physically inspired sound synthesis methods for the creation of computer generated music. To this end, a software library has been developed for the purpose of the real-time simulation of systems of inter-connected 1D and 2D objects to be assembled by the user. Although the developed software has proven to be indispensable for producing the creative results, the emphasis of assessing the research should be on the contribution of the portfolio to the field of musical invention, as the goal was not to add any novel technical knowledge to the field of physical modelling. Instead, my aim was to explore in depth the creative possibilities of technical research carried out by others and to show that it can be utilised in a form which aids my own creative practice. From a creative perspective, it builds upon concepts and ideas formulated earlier by composers Jean-Claude Risset and Denis Smalley, centered around the interpretation of timbre and sound as constructs which actively inform compositional decision-making and structuring processes. This involves the creation of harmony out of timbre and playing with the source-cause perception of the listener through the transformation of timbre over time. Lastly, the thesis offers a discussion of gesture and texture as they commonly appear in electroacoustic music and tries to justify my own personal preference for focusing on the development of texture over time as a means to create musical form and function.
The Sound of Memory: An artistic exploration of personal and cultural narratives in post-conflict communities.
Supervisors: Paul Stapleton, Martin Dowling
Through a creative portfolio and reflective writing, this thesis explores how divergent sound-art practices can represent oral history narratives found in post-conflict societies such as Northern Ireland and Bosnia. Recently collected interview materials have been transcribed, edited and transformed through the application of a newly devised artistic methodology, which draws on verbatim theatre. This re-telling of personal narratives takes place through intertwining the practices of verbatim song-writing, sound design, live performance and installation art. The primary aim of this research is to increase access to the often forgotten knowledge found in individual experiences, thus augmenting more generalised historical narratives of marginalised communities.
Ambisonics and Higher-Order Ambisonics for Off-Centre Listeners: Evaluation of Perceived and Predicted Image Direction
Supervisors: Maarten van Walstijn, Stephanie Bertet
Higher Order Ambisonics is a spatial audio technique that aims to recreate a sound image over as large a listening area as possible. Only limited investigation has taken place into localisation with Ambisonics and Higher Order Ambisonics at off-centre listening positions. This thesis presents the results of three psychoacoustic localisation experiments investigating off-centre localisation of first and third order Ambisonics under different conditions: in acoustically damped studio conditions, investigating transient versus ongoing, non-transient stimuli for the third order system, and for a large array system with increased arrival time delay between loudspeakers. A detailed analysis of the results of each experiment is carried out to determine the robustness of the tested ambisonic systems and whether the variation is principally due to differences between listeners or through the variation of individual listeners. Comparisons are made between the results of the three experiments to determine the influence of changing the stimulus or increasing the arrival time delay between loudspeakers, where the relative gains of the loudspeakers was found to be perceptually more important than increased time differences between them. The significance and usefulness of these results can be increased by comparison with models for prediction of human localisation, where a robust model would afford fast evaluation of ambisonic systems and allow system optimisation for off-centre positions. Therefore, evaluation is performed for two binaural models on their ability to predict the results of the psychoacoustic experiments. This includes a model that has previously been used for prediction of off-centre listening positions for higher order systems and WFS. A modified version of the Lindemann model, which includes a precedence effect inhibition, is also evaluated, having previously been applied to two channel lead-lag experiments. Finally, the energy vector model, which is prevalent in the Ambisonics community, is extended to include elements of the precedence effect. The binaural models, the standard energy vector, previously untested for off-centre positions, and the precedence-extended model are evaluated by comparison to the perceptual results. The robustness of each of the binaural and vector models is discussed in the context of their use as predictors of localisation at off-centre listening positions. The predictions of the precedence-extended energy vector are found to exhibit the lowest deviation from the perceptual results.
Niall Fredrick Coghlan
Physiological Correlates of Emotion as Interaction Channels with Artistic Applications: Artwork and Experiments
Supervisors: Paul Stapleton, Ben Knapp
Links between music and emotional state have been posited for many years, dating back to Aristotle, and periodically taken up by musicians, musicologists, philosophers and most recently neuroscientists. Mounting evidence suggests that music is used by many as a form of mood regulation and there is a long history of music as therapy, usually realised as performance or group work, with more recent studies showing links between music listening and positive healthcare outcomes.
In addition to interest in the relationship between music and emotion, there has been a recent upsurge in research into emotion as a channel for technological and creative interaction with music, multimedia artworks, computers and new digital instruments. It is exploring this aspect of emotion-based interaction that provides the motivation for this thesis, a desire to utilise emotion (and the physiological characteristics associated with affect) as an interaction channel. In order to achieve this, further exploration of the associations between emotion, physiology and music is necessary.
To date studies in the field of music and emotion have faced a number of challenges, not least in the definition of and delineation between emotions, moods, feelings and other affective states. Other challenges include limited sample sizes in experimental work, a past focus on the western classical tradition and the difficulties involved in ecological assessment of emotion.
As context for my own work, this thesis initially presents an overview of the dominant theories relating to emotions, and in particular their interaction with music and the mechanisms and audio features by which music may induce emotion. An overview and critique of artworks utilising signifiers of affective state is also presented before detailing my own artistic contributions as co-creator of artworks utilising physiological correlates of emotion. An overview of a large-scale public experiment (Emotion in Motion) designed to explore and deepen knowledge of some these issues is presented, along with an analysis of the data collected. This analysis found relationships between specific musical features such as tempo, mode and dynamic range and participant experiences of factors relating to emotions such as valence, arousal and engagement.
The concluding chapter summarises the findings and examines potential directions for future research as well as applications of emotionally and physiologically aware technologies, including affective computing, healthcare and interactive artworks.
Microsound: A Portfolio of Original Compositions
Supervisors: Paul Wilson, Pedro Rebelo
This portfolio of six electroacoustic compositions and accompanying thesis present an investigation of microsound through a variety of lenses.
Microsound is defined as both sound particles consisting of extremely short transients, and also sounds containing low amplitude levels. In this research I investigate how considerations of microsound can influence and shape compositional decisions, and show how this influence can be traced within my own compositional approach. The six compositions that comprise the portfolio explore different aspects of dynamic and temporal microsound, as well as microsound in relation to concepts of noise. The compositions are: Surface (2010), a two-channel piece for tape that examines microsound in relation to soundscape and listening and recording spaces; Testure (2011), composed for a combination of two and five channels, investigates microsound via an exploration of masked
audio contained in instrumental sound sources; Bunker (2012) and Odessa (2012), interconnected compositions composed, respectively, for eight and sixteen channels, examine short transient audio fragments in the context of noise and rhythm; Mochorel (2013), a two-channel piece, which proposes the idea of ‘noisescape’ as a merging of soundscape composition and noise; and finally ParkerSuite (2013), a work for GPS-enabled mobile /phones that was created in the context of an umbrella Project, Belfast Soundwalks, in which compositions are mapped to real-world environments using mobile app technologies. This last composition explores naturally occurring microsounds within the environment, e.g. birdsong.
The six compositions in the portfolio are linked thematically as well as through the application of different microsound compositional techniques. The thesis shows how each composition developed both as a standalone work and in relation to the larger portfolio, and demonstrates a strong connecting thread between the different works. The commentary further explores in-depth the concepts and techniques explored in the portfolio, and situates these ideas within an historical context. Historical influences range from Futurist ideas of noise to John Cage’s concept of ‘small sounds’; the compositional ideas and methods of lannis Xenakis, Karlheinz Stockhausen, Morton Feldman, Jakob Ullman and others; and musicological and theoretical concepts put forward by Curtis Roads, Dennis Smalley, Kim Cascone, Joanna Demers, R. Murray Schafer, and others. Through the different compositional investigations and associated discussions I conclude that microsound offers a rich avenue through which to explore contemporary ideas and methods in electroacoustic music, and show how these ideas can be effectively applied in a variety of ways.
Abstracted Materials: A Composition Portfolio
Supervisors: Eric Lyon, Pedro Rebelo
This commentary will discuss the main concepts behind the electroacoustic music in the composition portfolio: Abstracted Materials.
Produced between the years of 2008 to 2013 at the Sonic Arts Research Centre, Queen’s University Belfast, these acousmatic works will be framed within various contexts, from the practical to the theoretical. Occasionally, the analysis will centre upon the strategies and methods applied to the formal aspects of the compositions and also consider ideas associated with listening as an integral aspect of sound art practice.
During the time I attended the Sonic Arts Research centre, the research encountered many shifts: from the psychoacoustic aspects of a sound, or sound making activity as a source of inspiration, to the intuitive use of materials that formed my personal associations with a musical process. This document attempts to weave a narrative from these experiences. My goal is to explain these musical concepts and to faithfully record the process of producing this portfolio of acousmatic works.
Lilian Lima Simones
The roles of gesture in piano teaching and learning
Supervisors: Franziska Schroeder, Matthew Rodger
The experience of engaging with music through listening, teaching and learning would be impossible without a bodily interface, through which movement and music can be physically produced, experienced and understood. Physical gestures form a central part of the communication established between the teacher-student dyad in the communication of symbolic and functional musical knowledge. Factors such as gesture types (forms and meanings) and their specific outcomes in the teaching and learning processes have been consistently overlooked in the instrumental music pedagogical context. This thesis prioritises such undervalued topics, focusing its enquiry upon piano teachers’ hand gestures used to communicate with students during the teaching process and incorporates theoretical frameworks from disciplines such as: music-psychology, psycholinguistics, gesture studies, gesture-led educational re-search, imitation and observational motor-learning.
Three investigations were carried out to investigate the role of teachers’ gestures in piano teaching and learning. The first two combined qualitative and quantitative approaches – the results of which were used in establishing the first known categorisation of piano teachers’ gestures. Amongst the most intriguing findings were the relationship between teachers’ didactic intent and the forms of gesture they employed, and ‘gestural scaffolding’ (when teachers adapted particular gestural communicative channels to suit specific student skill levels). In the third investigation an experimental setting was used to observe and evaluate the role of teaching gestures in one-to-one instrumental tuition. Here different gestural teaching and learning conditions yielded multiple levels of learning effectiveness, implying a need for empirical understanding and establishment of gestural performance as a concept that can be applied to enhance learning across specific pedagogical contexts. As well as building a case for future investigations in this research area, this thesis opens a debate within studies of pedagogical practice in instrumental music teaching, whilst contributing more generally to discussions of how the body impacts upon music understanding.
What does it mean to perform sound? As an artist who began his career creating sound design and improvising with performance artists, choreographers and theatre directors, I came to understand that every aspect of the construction of an event matters: body, text, place and sound. It is this interdisciplinarity — alongside the move from conventional performance spaces to outdoors — that prompts me to propose a post-medium approach (Krauss 2000), considering everything that happens in and around sound as significant to its performance (Kim-Cohen 2009). This approach concentrates on the ethics (Morton 2007) of constructing a site-specific interaction (Kwon 2002, Turner 2004) between place, performer and sonic experience; that focuses on sonic performance as a relational site of encounter instead of reception (Bourriaud 2002); explores the intersubjective, multi-sensorial (Ingold 2000) and creative potential of the subject; and considers the “noise” of thoughts and existence not as a distraction from entering a sonic experience, but ultimately as an essential part of listening (Nancy 2007, Ihde 2007).
Performing sound thus complicates traditional separations between music and sound art, as a result of medium specificity or context (Licht 2007), and becomes a process in which the expre
Territories of Secrecy: Presence and Play in Networked Music Performance
Supervisor: Pedro Rebelo
This thesis presents practical work and theoretical research spanning topics in music composition, performance and new media. It proposes a particular creative approach to performance practices mediated by computer networks, which addresses issues of presence and liveness through the application of game-derived systems to performance settings. The thesis includes a portfolio of eight compositions; these pieces were designed and performed with the goal of implementing strategies proposed during theoretical reflection, while also suggesting new ideas for further study.
The theoretical component of this work investigates the notion that performance is affected in its attributes of presence and liveness whenever reproduction and mediation technologies come into play. Building on the views of media theorists and research in psychology, it identifies the roles played by agency and social cues in the perception of presence. After reviewing contemporary artistic practices in which participation is enabled by open and playful performance situations, the thesis proposes the use of game systems as a strategy for negotiating musical play in networked settings.
The notion of secrecy provides a key conceptual reference that guides both theoretical enquiry and creative exploration. This investigation argues that every act of mediation entails an opportunity for selective concealment of ideas and actions, and therefore comprehends a wide creative potential. While music performance over computer networks may entail the loss of cues that are often taken as granted in ensemble play – such as shared pulse, breath and bodily communication – it may also suggest innovative modes of engagement, based on the regulation of information rather than its unimpeded disclosure. This premise is explored throughout the portfolio, which borrows ideas from contemporary social practices of secrecy and performativity.
Emotion Recognition from Physiological Indicators for Musical Applications
Supervisors: Ben Knapp, Maarten van Walstijn
This thesis investigates the emotional response of audiences to music via physiological indicators, with the goal of creating interfaces that use emotional state for music control, specifically in performance scenarios via electrodermal and cardiovascular measures. In the past two decades, multiple disciplines have shown interest in studying the relationship between music, emotion, and its physiological manifestation. However, despite the increasing attention, the actual mechanisms on how music modulates human emotion and how this correlates with physiological changes are still not well understood. Therefore, this topic provides interesting challenges to determine if musical emotions can be measured from audiences in ecological environments via physiological signals. In order to address this, there are several questions that need to be resolved; including how to measure physiological indicators of emotion in concert environments, what level of shared responses and variance can be expected from public audiences, and how to assess the induction of musical emotions on listeners. In order to answer these questions, the work in this thesis starts by measuring physiological indicators of emotion in music concerts, revealing high correlations between the physiology of performers and audience members, as well as associations between physiological changes and structural and acoustical features of the music. In order to assess felt emotion on listeners and how these are manifested via changes in physiology, a series of modular public listening experiments (Emotion in Motion) were implemented in Dublin and New York, collecting physiological data and self-report measures of emotion from over 4000 participants. Analysis of this database reveals a set of specific physiological indicators that show significant relationships with musically induced emotions. This thesis also contributes robust feature extraction tools for Electrodermal Activity and Heart Rate, and a methodology for synchronization of multimodal signals for musical performance research.
Numerical Simulation of Coupled String Vibrations with Application to Physics-Based Sound Synthesis
Supervisors: Maarten van Walstijn, Colin Cowan
The work in this thesis presents and discusses new techniques for modelling string instrument vibrations for the purpose of physics-based sound synthesis. The work focuses on coupled systems, where phenomena such as sympathetic vibrations should naturally occur. Finite difference (FD) methods are chosen for modelling string vibrations for their flexibility both in terms of local adjustments and possible extensions to non-linearities. The resonating body is represented using a modal formulation. Modelling the body in such a way has the advantage of scalability which can improve efficiency. This is shown to be possible without affecting the overall timbre of the sound. The models were formulated using idealised shapes such as the beam and plate, but the modal formulation is general for all linear systems. A technique for interfacing the FD model of the string to the modal formulation of the body is presented. In this way the advantages of both methods are exploited, improving the balance between accurate and efficiency. Initially, this coupling is formulated using only transverse motion but is then extended to include longitudinal motion. In simulations of a harp-like instrument where the strings are coupled to the body at an angle, results obtained with numerical experiments show that including longitudinal vibrations impacts the eigenmodes of the system and prove essential for accurately modelling sympathetic vibrations. Comparisons with previous studies validate these results. By applying the proposed method to model resembling a simplified piano, online changes to parameters such as soundboard density further demonstrate the proposed technique.
A Portfolio of Original Compositions
Giovanni de Sanctis
In-System Parametric Calibration for Two-Microphone Wave Separation in Acoustic Waveguides
Supervisors: Maarten van Walstijn, Colin Cowan
The separation of waves in acoustic waveguides can be used to infer information from various acoustic systems. When applied to musical wind instruments, it allows novel techniques for in-depth investigation of the physics of the instrument, including the extraction of playing information in wind instruments, bore reconstruction and impedance measurement. Although a few approaches to this problem can be found in the literature, little attention has been given to the calibration of the system and above all to the assessment of its performance. The proposed methodology is based on a frequency-domain optimisation of a small set of parameters that best describe the system. The nonlinear optimisation problem that arises is formulated in order to exploit the considerable amount of a-priori knowledge given by the theory of propagation in ducts. The resulting cost surface is typically characterised by several local minima; however, the initial guess given by the nominal values for the parameters ensures the convergence to the desired solution. The main feature of the optimisation approach is that it can be applied in system and does not require any special calibration apparatus. As a consequence, it is also possible to track slow variations in the propagation due to changes in temperature and humidity of the medium during normal operation. A procedure for the assessment of a wave separation algorithm is also proposed; this shows that, under the same conditions, the optimisation approach improves the performance of the system. Finally, the proposed frequency-domain optimisation is also suitable for other applications such as in-air direction of arrival estimation. Preliminary results on these applications are also presented.
A portfolio of original compositions
Supervisor: Paul Wilson
A collection of original works are presented that explore a broad spectrum of compositional possibilities.
Five open form non-linear works are introduced as sound toys. These are designed to be exploratory and playful compositional frameworks, or systems for composition, that are relevant to the fields of sound art and electroacoustic music. Compositional decisions are controlled or influenced by an end user (or player) in these playful open form works. Multidisciplinary compositional approaches and alternative mediums for the presentation and dissemination of electroacoustic artworks are investigated.
Five fixed media electroacoustic pieces are presented. Ideas of kinesis and kinetic energy as an external compositional agent, and multichannel spatial approaches are central to these works.
Cross-pollination of aspects of both aesthetic and technical concerns of each discipline are explored, and these fields have been allowed to feed each other.
In and Out of Context: Field Recording, Sound Installation and the Mobile Sound Walk
Supervisor: Pedro Rebelo
This thesis chronicles the practical and theoretical research that has been undertaken in conjunction with, and in support of, the creation of a portfolio of original works. The portfolio comprises five works of sound art: two are sound installations, and three are what I call ‘mobile sound walks’. All five works are site-specific, meaning that they have been designed for a specific space, in response to a specific social and environmental context, and take into account the cultural, historic and political significance of the hosting site.
The first half of this thesis is dedicated to an in-depth discussion of the work of six artists with whom I align my own creative practice. These include the composers Pierre Schaeffer, Luc Ferrari and R. Murray Schafer, who are noted for their use of everyday sounds as compositional material; the sound installation artists Max Neuhaus and Bill Fontana, who create site-specific, environmental sound art works; and Janet Cardiff, a pioneer of mobile sound art.
In the second half of this thesis I provide a detailed analysis of my own work, with a particular focus on my mobile sound walks, which use location-aware technologies as a means to map sounds across a landscape. Such technologies have received little attention through existing sound art discourses. This thesis addresses this lack, by offering conceptual perspectives and methodological tools for understanding and producing what I call ‘locative soundscape composition’.
Throughout this thesis I draw upon a range of critical theories and method- ologies both from within, and from outside of, sound art studies, which help to shed new light on sound as it relates to, for example, the city, the politics of everyday life, the production of space and place, and the relationships between site-specific art, urban environments, and social actors.
Physical Modelling Sound Synthesis by Digital Waveguide Extraction with Application to Computer Games and Virtual Environments
Supervisor: Maarten van Walstijn
While the first computer games synthesised all their sound effects, a desire for realism led to the widespread use of sample playback when technology matured enough to allow it. However, current research points to many advantages of procedural audio which is generated at run time from information on sound producing events using various synthesis techniques. A physical modelling branch of synthesis has emerged, primarily from research into musical instruments, and this has provided audio synthesis with an intuitive link to an environment's virtual physical parameters. Some physical modelling techniques, primarily modal synthesis, have been used to synthesise audio in real-time in interactive virtual environments.
This thesis presents a new technique called digital waveguide extraction which models the motion of a two dimensional membrane. The technique exploits the efficiency advantages of digital waveguides, which are commonly used to model one dimensional objects, by extracting harmonic subsets from the membrane's spectrum based on plane waves travelling in a single direction. The technique is shown to be mathematically equivalent to modal synthesis. A detailed method of implementation is provided, the output of which is shown to closely match that of modal synthesis in frequency content and amplitude envelope. A means of decreasing the computational complexity of the technique, while affecting minimal change to the synthesised sound, is proposed and justified. The saving can be applied to a varying degree which is useful in environments where objects can have different levels of perceptual importance and processing availability can vary due to factors unrelated to audio. Perceptual listening tests reveal that, without affecting any perceptual di erence to the sound produced, the computational complexity can be reduced by at least 72%, typically around 95% and under some circumstances beyond 99%.
Finally, the digital waveguide extraction technique has been linked to a purely geometrical analysis of a membrane. This provides an alternative understanding of the technique and indicates potential for a new wave-based approach to modelling non-ideally shaped objects and rooms.
The Piano and The Female Body: the Erotic, the Seductive and the Transgressive
Supervisor: Pedro Rebelo
This thesis proposes an “erotics” of music performance based on a close analysis of the relation between the female body, the piano and the body of the spectator. This practice-led research consists of a written thesis and five original performance works using choreography, installation, film and photography.
As a pianist specialising in contemporary repertoire I have a particular interest in the overlap between gesture-based choreography and music performance. Through “embodied improvisation”, I explore physical expression in virtuosic repertoire using the analogy of sexual metaphor. Presenting the tactile relation between the female body and the piano as a concupiscent exchange of energies and desires, I propose a feminisation of the piano and the pianist's body based on the writings of Richard Leppert (1995 ) and Susan McClary (2002 ). Using choreographic theory I suggest “full” and “empty” body approaches to conceiving physical expression in music performance and how such approaches reflect on notions of gender ambiguity, abjection and the gaze (Butler: 2008 ), (Claid: 2006), (Kristeva: 1982 ) and (Mulvey: 2006 ). The thesis concludes music performance as a seductive and transgressive act, supported by emerging theoretical findings and realised through original interdisciplinary practice-led research (Bataille: 2006 ) and (Baudrillard 1990 ).
The representation and control of time in tangible user interfaces (designing musical instruments for the manipulation of temporal media)
Musical applications of tangible interfaces are successful because they solidify the ephemeral sounds and structure of music, presenting them to player as readily graspable bricks, pucks and tangible objects. This thesis proposes that a detailed study of how time may be used within tangible interfaces is required in order to allow a better understanding of how to design new systems with this capability.
Music and sounds are not existing physical objects; therefore representing them as objects provides the designer with a very wide selection of possibilities. Rather than following a prescriptive route of giving the designer a set of guidelines, this thesis takes the more open approach of creating a design-space and interaction model that can help synthesise new design ideas, helping to draw attention to lesser explored areas.
This thesis proposes and evaluates the temporal-MCRit interaction model; a conceptual model of how time can be used in tangible user interfaces, adapted from a standard TUI model. This new interaction model can be used to both analyse existing systems, and synthesise new ones. The aim in proposing the interaction model is to encourage the design of tangible interfaces that go beyond a simple spatial mapping of time, towards future designs that allow fluid, intuitive interaction with temporal digital media. The BeatBearing tangible rhythm sequencer is presented in this thesis as an instrument designed to explore the tTUI design space and develop the interaction model. Variations of the BeatBearing are compared to evaluate the ability of the temporal-MCRit in assisting the designer of new temporal-TUIs.
Forward and inverse modelling of single-reed woodwind instruments with application to digital sound synthesis
Supervisor: Maarten van Walstijn
Physical modelling of musical instruments aims to translate a set of physical model parameters into audio, by simulating the sound generation mechanism of the instrument(physics-based synthesis). The inverse process, physics-based analysis, addresses the extraction of the physical model parameters from the oscillations of the instrument.
Focusing on single-reed woodwind instruments, the main objective of this study is to formulate such an inverse modelling approach. Given a natural sound, measured under real playing conditions, physical model parameters are extracted, so that they can be used to resynthesise the original sound.
Under this inverse modelling scope, a physical model of the clarinet is created, with special focus on its non-linear reed-mouthpiece system. A two-dimensional distributed model is formulated, in order to study the mechanical behaviour of the reed, in the absence of acoustic feedback. This model is used to inform a lumped model formulation of the reed. Complex fluid dynamical phenomena are also incorporated in the lumped model, which is then coupled to a linear model of the instrument bore, to form a virtual representation of a clarinet.
Based on this lumped model formulation, the inverse modelling process consists of a two-step optimisation routine. Given the pressure and flow signals in the mouthpiece, the first step uses a parametrised relationship between the pressure and flow in the mouthpiece in order to estimate the parameters of a simplified model. Starting from this parameter set and simulating the oscillations of the instrument, the second optimisation step estimates the lumped model parameters, trying to match the original and the resynthesised sound. The accuracy of the process is tested based on a set of numerically synthesised data. Finally, the model is applied to various sets of measured data and the robustness of the parameter extraction process is discussed.
A Portfolio of Audiovisual Compositions for the ‘new media everyday’
Supervisor: Pedro Rebelo
By examining three audiovisual compositions, A Natural Balance (2006), Pixel Parasites (2006) and Thrice Removed (2008), this thesis explores an approach that attempts to tackle problems associated with composing in the new media everyday. Each composition, which together I refer to as the ‘audiovisual portfolio’, addresses different aspects of the new media everyday. In a similar manner to television, film and videogames, the portfolio exploits computer graphics and sound manipulation techniques. However, there is an abundance of audiovisual content in the new media everyday. This thesis discusses the portfolio with respect to such content and covers issues relating to artistic communication in our creatively crowded society. It analyses the portfolio as both a critical response to, and an inescapable by-product of, the rich audiovisual experiences of our daily lives. In addition, it tackles the contradictory ways these experiences both excite and anaesthetise our senses.
The Revolution is Hear! Sound Art, the Everyday and Aural Awareness
Supervisor: Pedro Rebelo
This thesis presents a body of practical and theoretical work, which interprets sound art as a means of encouraging aural awareness in an everyday context. Through a methodological feedback loop of artistic practice and theoretical re- flection, strategies for the aestheticisation of everyday aural experience have been developed and situated within a wider context of contemporary aural cul- ture. The current state of this culture is critically examined. The widespread claim that we live in a deeply visualised culture is questioned. It is argued that contemporary Western society can also be characterised in terms of an increasing interest in auditory perception, which the development of sound art as an artistic discipline is one symptom of The technological mediation of listening is discussed and characterised in terms of a mobilisation and individ- uation of aural experience. An overview of different listening modes informs a discussion of six different perspectives on sound as a physical and perceptual phenomenon. Various listening practices, which have been proposed in the field of sound art, are presented. It is argued that the development of sound art as an artistic discipline can be characterised in terms of an interest in the everyday as a source of sound material on one, and as an environment for aestheticised listening on the other hand. Sound art is proposed as a means of auralising the rhythms inherent to everyday life, and subtlety is identified as an aesthetic category for doing so. It is investigated how technological mediation can be applied to the aestheticisation of mobile and social listening experiences. The above issues have been addressed by means of artistic practice. The results of this process are presented as a portfolio of eight artworks, including sound installations, public interventions, site-specific electroacoustic pieces, graphical scores and mobile hardware projects.
Towards an Idiomatic Compositional Language for Biosignal Interfaces
Supervisors: Ben Knapp & Michael Alcorn
This thesis presents a systematic approach to music composition with and for biosignal-driven interfaces. It gives a general view of the historical developments of biosignal-related art over the last forty four years, discussing the various ways in which artists have approached the creation of works that are driven by the electric physiological signals generated by the human body. It questions some of the established paradigms for physiological-level interaction between performers and musical systems, and proposes a model in which biosignals can be regarded as elements in the definition of novel musical instruments. It presents a set of technical hardware and software tools that allow for the easy and rapid deployment of biosignal interfaces as well as a conceptual framework for music creation based on physiological signals. It discusses a series of music compositions that where created before this framework was defined, outlining the shortcomings of these works and further presents a set of works that were created following the ideas presented in this thesis. It establishes a quantifiable difference between both sets of pieces, and how an idiomatic model can be applied to biosignal-driven instruments in order to take advantage of their inherently musical characteristics for musical creation.
The Network as a Performance Space: Strategies and Applications
Supervisor: Pedro Rebelo
A portfolio of original compositions
Supervisor: Michael Alcorn
The Ear of the Beholder: Ecology, Embodiment and Complexity in Sound Installation
Supervisor: Pedro Rebelo
This thesis presents a body of practice and theory based work, based on a study of an application of models from Complexity Theory to music creation, with a focus on Artificial Life inspired techniques applied as musical processes. It identifies two important issues that are subsequently explored through the creation of sound installations. Firstly, issues pertaining to the employment of models from the field of Complexity Theory for the creation of music; a concern with transference of metaphor, a regrounding of referents in the specificity of music. Secondly, through a discussion of the employment of process in music it identifies a need to employ generative techniques that are more open in their nature, both on a structural and an interpretive level. It thus proposes a conception of process that is open in an ecological sense, in which a level of agency is prescribed to the technological agents that construct the installations, their environmental context and the human interactants within this context. It outlines a body of sound installations that exploit a concept of emergent musical structures as a process of timely perception, rather than fixed objects of empirical observation. In this conception, aesthetic meaning came forth not through the transitivity of the object but through the process of conjoined action between agents, the environment and the human interactant. This thesis formulates an understanding of sound installation as a situated and timely act that is best understood from an embodied, ecological perspective and develops a conception of engagement that is contingent on space, place and personal subjective experience. It outlines strategies that were developed through the process of creative practice for the creation and perception of complexity that exploit notions of embodiment within installation design.
Boundary and medium modelling using compact finite difference schemes in simulations of room acoustics for audio and architectural design applications
Supervisor: Maarten van Walstijn
Simulation of acoustic spaces with the aim of developing virtual immersive applications and architectural design applications is one of the key areas in the field of audio signal processing. In this thesis, a complete method for simulating room acoustics using compact finite difference time domain (FDTD) schemes is presented.
A family of compact explicit and implicit schemes approximating the wave equation is analysed in terms of stability, accuracy, and computational efficiency. The most accurate and isotropic schemes based on a rectilinear nonstaggered grid are identified, and the optimally efficient explicit schemes are indicated.
Novel FDTD formulations of frequency-independent and frequency-dependent bound- aries of a locally reacting surface type are proposed, including a full treatment of corners and boundary edges. In particular, it is proposed to model generally frequency-dependent boundaries by local incorporation of a digital impedance filter (DIF), and the resulting formulae for compact explicit schemes are provided. In addition, a numerical boundary analysis (NBA) procedure is proposed as a technique for analytic evaluation of the numer- ical reflectance of the presented boundary models. The digital impedance filter model is also extended to model controllable surface diffusion based on the concept of phase grating diffusers.
Results obtained from numerical experiments and numerical boundary analysis confirm the high accuracy of the proposed boundary models, the reflectance of which is shown to closely approximate locally reacting surface theory for different angles of incidence and various impedances. Furthermore, the results indicate that boundary formulations based on the identified accurate and isotropic schemes are also very accurate in terms of numerical reflectance, and outperform directly related methods such as Yee’s scheme and the standard digital waveguide mesh. In addition, one particular scheme - referred to as the interpolated wideband scheme - is suggested as the best FDTD scheme for most audio applications.
Developing an assistive haptic framework for improving non-visual access to the web
Supervisor: Graham McAllistair
Haptic technologies have the potential to help the blind community overcome many of the challenges experienced when accessing the Web. With limited design guidance available to web developers, haptic effects could be selected arbitrarily for use on a web page, with minimal consideration given as to how the sense to touch could assist a blind user. Poor interface design is known to reduce the quality of the subjective browsing experience. In this thesis, research has been conducted with the aim of developing effective spatial and navigational cues to address issues of accessibility on a web interface. Using a structured participatory-based design approach, force-feedback cues have been developed to represent objects commonly found on a web page (e.g. images and hyperlinks). The application of a modified version of the approach, has led to the design of tactile pin-based stimuli, which provides similar levels of structural and navigational support to the force-feedback cues. Findings have informed a library of software, with accompanying guidelines for their application on a web page. These are housed within a haptic framework. This tool provides a vital reference for developers, allowing them to replicate effects on their own sites, and offers support during both the design and evaluation processes. It is left to the discretion of the developer to include the mappings that are most appropriate to the context of the web-based task, and ensure that these cues are targeted to the needs of a broad range of blind individuals when using a tactile or force-feedback device.
Chui Chui Tan
An adaptive architecture to support web graphics exploration for visually impaired people
Supervisor: Graham McAllistair
This thesis employs a user-centred approach to design and develop an extensible, adaptive system, the ACTIVE system to improve Web graphics accessibility for visually impaired people. It is capable of adapting to its context of use such as graphics type, assistive technologies and user profiles in order to choose a suitable graphical multimodal application for the user. Additionally, the system consists of a user model which contains information about a user in terms of their background, experience levels, and preferences. By performing a series of experiments with visually impaired people, it reveals that people with similar profiles and experience levels prefer certain exploration conditions. Consequently, a list of adaptation rules have been derived and applied in the system. By using a feature-based approach, the ACTIVE system learns about the users from their previous interaction with applications and presents to them with their most preferable and appropriate interface. The ACTIVE system was designed in accordance with usability and accessibility guidelines. The system was evaluated with visually impaired people and the results reveal that it has improved the overall experience and satisfaction of people with sight loss when accessing graphics non-visually. Furthermore, the adaptation accuracy level of the ACTIVE system increases with the degree of system use, where 96.67% of accuracy was achieved in the experiments. This thesis shows the possibilities in developing a coherent, adaptive system by integrating various variables such as graphics types, assistive technologies and multimodalities. It also demonstrates that adaptation can bring benefits to people with visual impairments in enhancing their graphics accessibility.
Dereverberation of acoustic signals via adaptive filtering
Supervisor: R Woods
This thesis investigates the blind dereverberation problem and proposes the use of predictive deconvolution as a tool for single channel dereverberation. Prediction deconvolution uses the principles of linear prediction to estimate a high order, minimum phase, inverse room impulse response directly from the reverberant audio signal’s linear predictive residual. Simulation results are present for speech and music sources reverberated with image-method generated room impulse responses. Due to the minimum phase property of predictive deconvolution and the nonminimum phase nature of rooms, higher-order statistics based adaptive filtering is also investigated. The subband kurtosis maximization adaptive filter is evaluated with speech and music sources. The room transfer function can be modelled as the product of a minimum phase and allpass component and predictive deconvolution, by reducing the effect of the minimum phase component, is shown to improve the stability and performance of the kurtosis maximization algorithm. Simulation results show up to 6dB reduction in reverberant error energy achieved with this combined approach. The use of linear predictive coding, to extract a decorrelated residual signal prior to dereverberation, is investigated with simulations demonstrating the effect of predictor order on performance. A sinusoidal-plus-residual model is proposed for audio signals with a large amount of harmonic content, such as the male singing voice, and shown to improve dereverberation performance. Finally listening test opinion scores are presented. These show that predictive deconvolution processed speech was judged to be closer to the anechoic source than the reverberant version by 65% to 70% of subjects; scores recorded for female speech processed with the combined predictive deconvolution and kurtosis maximization approach are higher than scores for kurtosis maximization alone.
A portfolio of original compositions
Supervisor: Michael Alcorn
This dissertation focuses on a portfolio of original musical compositions created at the Sonic Arts Research Centre between February 2003 and June 2006. The dissertation includes an analysis of the following works: Trans-mission; METROPOLIS ‘04; Terrestrial Variations; The orchestra of the noises of war ..; A letter from the trenches of Adrianopolis ...; Combine (after Rauschenberg); and Fuinneoga. In his critique, the composer puts forward his own internal reasoning for the compositional act and points to his understanding of what are the salient features of the portfolio, discussing issues of function, form, and control. In addition to the critiques, the portfolio includes scores, recordings, and software of the compositions discussed.
Inverse Methods in Room Acoustics with Under-Determined Data and Applications to Virtual Acoustics
Supervisor: Maarten van Walstijn
With the advent of commercial surround sound systems there is a growing demand for a system that can convert existing mono and stereo recordings into a surround sound recording. A part of this problem is to generate the reverberation for the additional audio channels from the reverberation in the mono or stereo recording. In this thesis, it is investigated whether a room model can be constructed from one or two room impulse responses and in which a virtual surround sound recording can then be performed. The estimation of the room model parameters is based on the three well-known room acoustic models; the geometrical acoustic model with specular reflections, the eigenmode model and the diffuse field model. It is shown that the scope with the geometrical acoustic and the eigenmode model is limited but it is possible to obtain useful and consistent results for the room volume and the source-to-receiver distance from the diffuse field model. Based on these findings, the problem of generating multiple room impulse responses from one or two input room impulse response(s) is approached slightly differently. The very early part of the room impulse responses (the early reflections) is generated by a geometrical model with specular and diffuse reflections. The remainder of the room impulse responses are copies of the input room impulses obtained by convolution with a set of filters that control the coherence between them. The values for the coherence are given by expressions for the coherence between microphones with first order directivity in a diffuse field and these expressions are derived in the thesis. The results from objective and subjective tests indicate that this method works successfully.
Portfolio of original compositions
Supervisor: Michael Alcorn
This Portfolio of Original Compositions highlights the development of my compositional approach during the years 2001 to 2004. Nine pieces of music are assessed: Rain between the Showers for tape, For Two for oboe, clarinet and trumpet, Jatayu for flute/piccolo/alto flute and 8-channel tape, dissolving into light for clarinet, viola and piano, One.. many for solo soprano, flute, oboe, percussion, double bass, 4 drum kits, DJ, small vocal ensemble, choir, Balinese gamelan and electronics, Enchant for tape, Around the Corner: Souvenirs of a day on Rathlin for high and low voice, kayagum and bass viol, Thar an bhfarraige gheal (Over bright sea) for seannós singer, Irish traditional fiddle, 3 violins, 2 violas, 2 cellos and tape and Music for Metropolis for amplified violin and double bass, electronics and tape.
Through this body of work, issues of style, technique, expression and form, and the roles of context, collaboration, intuition, compositional and pre-compositional processes are explored.