Peter Svensson: Sound field modeling for virtual acoustics

Abstract

The terms virtual acoustics and auralization have been used for around 20 years for the generation of computer simulations of sound fields that can be listened to. This tutorial will give a brief overview over the components involved: the source modeling, the modeling of an environment via an impulse response, and the rendering stage. The focus will be on the modeling og environments, with the categories of physical modeling and perceptual modeling. Furthermore, the physical modeling can be done by accurately solving the wave equation, or by geometrical-acoustics based methods. Possibilities and limitations with these methods will be discussed, demonstrating the various reflection components of specular reflection, diffuse reflection, and diffraction. Examples will be shown using the author’s Matlab “Edge diffraction toolbox” for generating animations of these phenomena.

Bio

Peter Svensson is professor of electroacoustics at NTNU since 1999. His main research interests are computational room acoustics, 3D audio techniques, measurement techniques, perceived room acoustical quality. He did a PhD on electroacoustic reverberation enhancement systems in 1994, at Chalmers University, Gothenburg, and has had research stays at University of Waterloo, Kobe University, Rensselaer Polytechnic Institute, and University of Reading. He has been president of the Norwegian acoustics society, vice president of the European Acoustics Association and associate editor for electroacoustics of Acta Acustica united with Acustica.

Øyvind Brandtsegg & Trond Engum: Cross-adaptive effects and realtime creative use

Abstract

Adaptive effects and modulations have been researched during the last two decades within the DAFx community, and cross-adaptive effects have been utilized for autonomous mixing and related applications. Current research into cross adaptive effects for creative use in realtime applications has led to the development of methods to incorporate these techniques into regular DAWs for audio production and performance. The tutorial will give insight into these methods, with practical examples on how to incorporate the tools in a DAW based workflow. Examples of use within live performance will also be presented.

Bio

Øyvind Brandtsegg is a composer and performer working in the fields of algorithmic improvisation and sound installations. His main instrument as a musician is Hadron Particle Synthesizer, ImproSculpt and Marimba Lumina. ImproSculpt is an instrument for live sampling and realtime composition. Hadron is a very flexible realtime granular synthesizer. In addition to his own work as a composer and musician, he has also 
done programming for other artists and for commercial audio applications. As musician and composer he has collaborated with a number of excellent artists. In 2008, Brandtsegg finished his PhD equivalent artistic research project, focused on musical improvisation with computers. Øyvind has done lectures and workshops on these themes in USA, Germany, Ireland, and of course in Norway.  Since 2010 he is a professor of music technology at NTNU, Trondheim, Norway.

Trond Engum is a composer and performer within the field of music technology. His main instrument is guitar and electronics. Engum has a background from bands like The 3rd and The Mortal and The Soundbyte, and have released several albums, played concerts and festivals since the mid 90`s. He has composed music for several theatrical performances and television programs. In January 2012, Engum finished his PhD equivalent artistic research project, focused on new strategies for composing and producing music using digital music technology. Since 2012 he is an associate professor of music technology at NTNU, Trondheim, Norway.

Xavier Serra: The AudioCommons Initiative and the technologies for facilitating the reuse of open audio content

Abstract

Significant amounts of user-generated audio content, such as sound effects, musical samples and music pieces, are uploaded to online repositories and made available under open licenses. Moreover, a constantly increasing amount of multimedia content, originally released with traditional licenses, is  becoming public domain as its license expires. Nevertheless, this content is not much used in professional productions. There is still a lack of familiarity and understanding of the legal context of all this open content, but there are also problems related with its accessibility. A big percentage of this content remains unreachable either because is not published online or because it is not well organised and annotated. With the Audio Commons Initiative we want to promote the use of open audio content and to develop technologies with which to support the ecosystem composed by content repositories, production tools and users. These technologies should enable the reuse of this audio material, facilitating its integration in the production workflows used by the creative industries. In this workshop we will go over the core ideas behind this initiative, then overview the existing audio repositories, technologies and production tools related to it, and finally outline the planned tasks to address the challenges posed by the initiative.

Bio

Xavier Serra is Associate Professor of the Department of Information and Communication Technologies and Director of the Music Technology Group at the Universitat Pompeu Fabra in Barcelona. After a multidisciplinary academic education he obtained a PhD in Computer Music from Stanford University in 1989 with a dissertation on the spectral processing of musical sounds that is considered a key reference in the field. His research interests cover the analysis, description and synthesis of sound and music signals, with a balance between basic and applied research and approaches from both scientific/technological and humanistic/artistic disciplines. Dr. Serra is very active in promoting initiatives in the field of Sound and Music Computing at the local and international levels, being involved in the editorial board of a number of journals and conferences and giving lectures on current and future challenges of the field. He has recently been awarded an Advanced Grant of the European Research Council to carry out the project CompMusic aimed at promoting multicultural approaches in music computing research. 

Marije Baalman: Digital audio out of the box - digital audio effects in art and experimental music

Abstract

While since the late 1990's laptops have become a common element in electronic music on stage, in recent years there is a move away again from the laptop, towards dedicated devices that perform one particular task. With the advent of platforms such as the BeagleBone, Raspberry Pi, but also Arduino, efficient computing of digital audio has found a large interest amongst artists who create their own instruments or sounding objects, usually within the context of open source software and hardware.

In this talk I will show various examples of these applications of digital audio in the field of art and experimental music; and discuss how their development and discourse is embedded in the open source movement.

Julius Smith & Kurt Wegner: Recent Progress in Wave Digital Audio Effects (part I & part II + video)

Abstract:

The digital audio effects (DAFx) community has contributed significantly to advancements in ``virtual analog'' modeling of classic audio effects in software.  Practicing musicians have enjoyed a growing list of classic analog gear available now as digital audio plugins as a result.

One competitive approach is the Wave Digital Filters (WDF) formulation pioneered by Alfred Fettweis. WDFs have been around since the early 1970s and have found much use in VLSI implementations of digital filters, where superior numerical robustness is especially important.  Since the early 2000s, this framework has been applied increasingly to musical acoustic modeling and digital audio effects, and its range of applicability has been recently expanded considerably to include arbitrary circuit topologies and multiple nonlinear elements.

The closely-related Digital Waveguide Framework (DWF) similarly uses wave variables (traveling-wave components) because wave-propagation delay lines can be implemented super efficiently as circular buffers.  As a result, it is straightforward to combine these two paradigms to yield wave-variable models of a mixture of distributed and lumped systems, such as a lumped hammer model striking waveguide string in the case of a piano model.

WDFs use wave variables in the context of lumped modeling where, by definition, wave propagation does not occur. How then can we understand the use of wave variables in WDFs?  This talk includes a somewhat alternative development of WDF principles based on the way that wave variables can be used to resolve implicit relationships in modular discrete circuit models.

The complexity of audio circuitry has often stressed the state of the art of WDFs, especially for nonlinear models. The DAFx community has contributed many new techniques in response.  This talk will review these contributions and point out remaining issues for future research in WDF theory.

In addition to their theoretical appeal, desirable energetic/numerical properties, and fine-grained modeling fidelity, WDFs are also attractive to virtual-analog algorithm designers as an elegant modular software framework. Implementing WDFs as a hierarchical object-orient tree in software such as C++ can yield readable and reusable code, with clear high-level descriptions of circuits and digital audio processing. We include examples of practical wave digital modeling, and demonstrations of real-time performance.

Franz Zotter: Ambisonic Audio Effects in Direction and Directivity

Abstract:

The properties of the spherical harmonics to represent patterns on the sphere, as well as their deep embedding in the acoustical wave equation, enable many nice audio effects in space.

First of all, the inherent smoothness of the finite-order spherical harmonic representations is the basis of Ambisonic amplitude panning on surrounding loudspeakers. The spherical harmonic representation is mighty enough to represent several directional effects, such as mirroring, rotation, directional loudness manipulation, directional warping in terms of a simple matrix multiplication.

What is more, the associated acoustic equations permit design and signal processing of not only microphone arrays for Ambisonic recording, but also spherical loudspeaker arrays for directivity synthesis.

The plenary lecture gives examples and explanations of freely available Plugins for Ambisonics (VST AmbiX plugin suite), and reveals a peek on adjustable directivity as a musical instrument.