Real-time sound synthesis on a multi-processor platform

Real-time sound synthesis means that the calculation and output of each sound sample for a channel of audio information must be completed within a sample period. At a broadcasting standard, a sampling rate of 32,000 Hz, the maximum period available is 31.25 μsec. Such requirements demand a large amount of data processing power. An effective solution for this problem is a multi-processor platform; a parallel and distributed processing system. The suitability of the MIDI [Music Instrument Digital Interface] standard, published in 1983, as a controller for real-time applications is examined. Many musicians have expressed doubts on the decade old standard's ability for real-time performance. These have been investigated by measuring timing in various musical gestures, and by comparing these with the subjective characteristics of human perception. An implementation and its optimisation of real-time additive synthesis programs on a multi-transputer network are described. A prototype 81-polyphonic-note- organ configuration was implemented. By devising and deploying monitoring processes, the network's performance was measured and enhanced, leading to an efficient usage; the 88-note configuration. Since 88 simultaneous notes are rarely necessary in most performances, a scheduling program for dynamic note allocation was then introduced to achieve further efficiency gains. Considering calculation redundancies still further, a multi-sampling rate approach was applied as a further step to achieve an optimal performance. The theories underlining sound granulation, as a means of constructing complex sounds from grains, and the real-time implementation of this technique are outlined. The idea of sound granulation is quite similar to the quantum-wave theory, "acoustic quanta". Despite the conceptual simplicity, the signal processing requirements set tough demands, providing a challenge for this audio synthesis engine. Three issues arising from the results of the implementations above are discussed; the efficiency of the applications implemented, provisions for new processors and an optimal network architecture for sound synthesis

Let Me Make it Simple for You

Discusses the creation and performance at a concert on Feb. 12, 1990, in the Merrill Ellis Intermedia Theater at the University of North Texas of three computer music-intermedia compositions: Shakespeare quartet for 4 acoustic guitars; A noite, porem, rangeu e quebrou, for instrument of low pitch range, tape and computer; and Help me remember, for performer, Synclavier, interactive MIDI computer music system and slides

The Macropolitics of Microsound: Gender and sexual identities in Barry Truax’s "Song of Songs".

This analysis explores how Barry Truax’s Song of Songs (1992) for oboe d’amore, English horn and two digital soundtracks reorients prevailing norms of sexuality by playing with musical associations and aural conventions of how gender sounds. The work sets the erotic dialogue between King Solomon and Shulamite from the biblical Song of Solomon text. On the soundtracks we hear a Christian monk’s song, environmental sounds (birds, cicadas and bells), and two speakers who recite the biblical text in its entirety preserving the gendered pronouns of the original. By attending to established gender norms, Truax confirms the identity of each speaker, such that the speakers seemingly address one another as a duet, but the woman also addresses a female lover and the man a male. These gender categories are then progressively blurred with granular time-stretching and harmonisation (which transform the timbre of the voices), techniques that, together, resituate the presumed heteronormative text within a diverse constellation of possible sexual orientations

The Macropolitics of Microsound: Gender and sexual identities in Barry Truax’s "Song of Songs".

This analysis explores how Barry Truax’s Song of Songs (1992) for oboe d’amore, English horn and two digital soundtracks reorients prevailing norms of sexuality by playing with musical associations and aural conventions of how gender sounds. The work sets the erotic dialogue between King Solomon and Shulamite from the biblical Song of Solomon text. On the soundtracks we hear a Christian monk’s song, environmental sounds (birds, cicadas and bells), and two speakers who recite the biblical text in its entirety preserving the gendered pronouns of the original. By attending to established gender norms, Truax confirms the identity of each speaker, such that the speakers seemingly address one another as a duet, but the woman also addresses a female lover and the man a male. These gender categories are then progressively blurred with granular time-stretching and harmonisation (which transform the timbre of the voices), techniques that, together, resituate the presumed heteronormative text within a diverse constellation of possible sexual orientations

Sample-level sound synthesis with recurrent neural networks and conceptors

Conceptors are a recent development in the field of reservoir computing; they can be used to influence the dynamics of recurrent neural networks (RNNs), enabling generation of arbitrary patterns based on training data. Conceptors allow interpolation and extrapolation between patterns, and also provide a system of boolean logic for combining patterns together. Generation and manipulation of arbitrary patterns using conceptors has significant potential as a sound synthesis method for applications in computer music but has yet to be explored. Conceptors are untested with the generation of multi-timbre audio patterns, and little testing has been done on scalability to longer patterns required for audio. A novel method of sound synthesis based on conceptors is introduced. Conceptular Synthesis is based on granular synthesis; sets of conceptors are trained to recall varying patterns from a single RNN, then a runtime mechanism switches between them, generating short patterns which are recombined into a longer sound. The quality of sound resynthesis using this technique is experimentally evaluated. Conceptor models are shown to resynthesise audio with a comparable quality to a close equivalent technique using echo state networks with stored patterns and output feedback. Conceptor models are also shown to excel in their malleability and potential for creative sound manipulation, in comparison to echo state network models which tend to fail when the same manipulations are applied. Examples are given demonstrating creative sonic possibilities, by exploiting conceptor pattern morphing, boolean conceptor logic and manipulation of RNN dynamics. Limitations of conceptor models are revealed with regards to reproduction quality, and pragmatic limitations are also shown, where rises in computation and memory requirements preclude the use of these models for training with longer sound samples. The techniques presented here represent an initial exploration of the sound synthesis potential of conceptors, demonstrating possible creative applications in sound design; future possibilities and research questions are outlined

Composing Music for Acoustic Instruments and Electronics Mediated Through the Application of Microsound

This project seeks to extend, through a portfolio of compositions, the use of microsound to mixed works incorporating acoustic instrument and electronics. Issues relating to the notation of microsound when used with acoustic instruments are explored and the adoption of a clear and intuitive system of graphical notation is proposed. The design of the performance environment for the electroacoustic part is discussed and different models for the control of the electronics are considered. Issues relating to structure and form when applied to compositions that mix note-based material with texture-based material are also considered. A framework based on a pure sound/noise continuum, used in conjunction with a hierarchy of gestural archetypes, is adopted as a possible solution to the challenges of structuring mixed compositions. Gestural and textural relationships between different parts of the compositions are also explored and the use of extended instrumental techniques to create continua between the acoustic and the electroacoustic is adopted. The role of aleatoric techniques and improvisation in both the acoustic and the electroacoustic parts are explored through adoption of an interactive performance environment incorporating a pitch-tracking algorithm. Finally, the advantages and disadvantages of real time recording and processing of the electronic part when compared with live processing of pre-existing sound-files are discussed

The Design and Evaluation of Computer Music Interfaces

The purpose of this research is to examine the methods employed to design a computer music system suitable for music composition purposes. The nature of an interface is introduced and discussed (Chapter 2), with particular reference to interfacing issues for computer music users. The nature of the user and the notion of a task in computer music are discussed and examined (Chapter 3), with outline methods for evaluations of users and tasks being introduced. Current computer systems design and analysis methodologies are introduced (Chapter 4), and subsequently adapted for use in computer music design and analysis applications. A set of guidelines is introduced in Chapter 5, specifically related to the design and analysis of computer music systems. These guidelines are formulated from the discussions regarding the interfacing requirements of a musician user and the nature of the tasks he wishes to accomplish employing computer related technology. An examination of several systems forms a major part of the thesis (Chapters 6 - 10), outlining a variety of available composition tools at the time of writing. Each system introduced and discussed is evaluated in relation to the guidelines introduced for design and analysis of computer music systems. An interface design case study (Chapter 11) employs the design methods introduced during the thesis, and highlights the need for intensive designer - user discourse

Composing Music for Acoustic Instruments and Electronics Mediated Through the Application of Microsound

This project seeks to extend, through a portfolio of compositions, the use of microsound to mixed works incorporating acoustic instrument and electronics. Issues relating to the notation of microsound when used with acoustic instruments are explored and the adoption of a clear and intuitive system of graphical notation is proposed. The design of the performance environment for the electroacoustic part is discussed and different models for the control of the electronics are considered. Issues relating to structure and form when applied to compositions that mix note-based material with texture-based material are also considered. A framework based on a pure sound/noise continuum, used in conjunction with a hierarchy of gestural archetypes, is adopted as a possible solution to the challenges of structuring mixed compositions. Gestural and textural relationships between different parts of the compositions are also explored and the use of extended instrumental techniques to create continua between the acoustic and the electroacoustic is adopted. The role of aleatoric techniques and improvisation in both the acoustic and the electroacoustic parts are explored through adoption of an interactive performance environment incorporating a pitch-tracking algorithm. Finally, the advantages and disadvantages of real time recording and processing of the electronic part when compared with live processing of pre-existing sound-files are discussed

Analysis and resynthesis of polyphonic music

This thesis examines applications of Digital Signal Processing to the analysis, transformation, and resynthesis of musical audio. First I give an overview of the human perception of music. I then examine in detail the requirements for a system that can analyse, transcribe, process, and resynthesise monaural polyphonic music. I then describe and compare the possible hardware and software platforms. After this I describe a prototype hybrid system that attempts to carry out these tasks using a method based on additive synthesis. Next I present results from its application to a variety of musical examples, and critically assess its performance and limitations. I then address these issues in the design of a second system based on Gabor wavelets. I conclude by summarising the research and outlining suggestions for future developments