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AES Amsterdam 2008
Paper Session P8

P8 - Wave Field Synthesis

Sunday, May 18, 09:00 — 12:30
Chair: Diemer de Vries, Delft University of Technology - Delft, The Netherlands

P8-1 The Theory of Wave Field Synthesis RevisitedSascha Spors, Technische Universität Berlin - Berlin, Germany; Rudolph Rabenstein, University of Erlangen-Nuremberg - Erlangen, Germany; Jens Ahrens, Technische Universität Berlin - Berlin, Germany
Wave field synthesis is a spatial sound field reproduction technique aiming at authentic reproduction of auditory scenes. Its theoretical foundation was developed almost 20 years ago and has been improved considerably since then. Most of the original work on wave field synthesis is restricted to the reproduction in a planar listening area using linear loudspeaker arrays. Extensions like arbitrarily shaped distributions of secondary sources and three-dimensional reproduction in a listening volume have not been discussed in a unified framework so far. This paper revisits the theory of wave field synthesis and presents a unified theoretical framework covering arbitrarily shaped loudspeaker arrays for two- and three-dimensional reproduction. The paper additionally gives an overview on the artifacts resulting in practical setups and briefly discusses some extensions to the traditional concepts of WFS.
Convention Paper 7358 (Purchase now)

P8-2 A Finite Difference Time-Domain Approach to Analyzing Room Effects on Wave Field Synthesis ReproductionRobert Oldfield, Ian Drumm, Jos Hirst, University of Salford - Salford, Greater Manchester, UK
Probably the largest pit-fall to accurate audio reproduction using wave field synthesis (WFS) is the listening space. The WFS theory assumes free field, source free conditions that are seldom the case for practical sound reproduction. There is consequently a need to determine what effect the reproduction room has upon the synthesized sound field. This paper presents a finite difference time-domain (FDTD) approach to predicting the sound field in a room with arbitrary geometry and frequency dependent absorbing boundaries. A significant benefit to using FDTD is that the WFS system can be modeled both as part of the room and also in free-field conditions; therefore distortion of the sound field from the acoustics of the reproduction room can be quantified.
Convention Paper 7359 (Purchase now)

P8-3 Wave Field Synthesis Evaluation Using the Minimum Audible Angle in a Concert HallGeorgios Marentakis, McGill University - Montreal, Quebec, Canada; Etienne Corteel, sonic emotion ag - Oberglatt, Switzerland; Stephen McAdams, McGill University - Montreal, Quebec, Canada
Localization accuracy with Wave Field Synthesis (WFS) was estimated in a variable-acoustics concert hall. Contrary to previous studies, we employed a Minimum Audible Angle (MAA) paradigm as a measure of localization performance. The MAA was estimated for three different listening positions, three orientations of the listeners (0, 60, 90 degrees) and two acoustical conditions. WFS was found to produce satisfying localization cues that depend little on the reverberation time of the room and only weakly on the position of the listener.
Convention Paper 7360 (Purchase now)

P8-4 Objective and Subjective Analysis of Localization Accuracy in Wave Field SynthesisJoseph Sanson, IRCAM - Paris, France; Etienne Corteel, sonic emotion ag - Oberglatt, Switzerland; Olivier Warusfel, IRCAM - Paris, France
This paper analyses localization inaccuracies in the synthesis of virtual sound sources using Wave Field Synthesis (WFS), particularly at high frequencies. Objective and perceptual analyses are conducted through a binaural simulation of the actual sound field reproduced at the listener’s ears. The simulation consists in summing the respective contribution of each array transducer after filtering it with the appropriate HRTF according to the considered listener’s position. High-pass filtered white noises are used as a critical signal to investigate the impact of aliasing on localization accuracy. Objective and perceptual observations show that localization accuracy may degrade for off-centered listening positions, which can be mainly attributed to a mismatch in the elicited Interaural Level Differences (ILD) above the aliasing frequency.
Convention Paper 7361 (Purchase now)

P8-5 Wave Field Synthesis with Increased Aliasing FrequencyEtienne Corteel, Renato Pellegrini, Clemens Kuhn-Rahloff, sonic emotion ag - Obergltt (Zurich), Switzerland
Wave Field Synthesis (WFS) is a sound reproduction technique that enables the synthesis of target sound fields without any assumption on the listening position. Spatial aliasing is one of the remaining artifacts of WFS that limits the exact synthesis below a corner frequency referred to as spatial aliasing frequency. This paper presents a new technique that enables an increase of the spatial aliasing frequency of WFS assuming a preferred listening area. The presented technique is fully scalable and may be adapted to any listening zone shape or location. Applications in the domain of simulation environments and home entertainment are discussed.
Convention Paper 7362 (Purchase now)

P8-6 Reproduction of Moving Virtual Sound Sources with Special Attention on the Doppler EffectJens Ahrens, Sascha Spors, Technische Universität Berlin - Berlin, Germany
In this paper we outline a basic framework for the reproduction of the wave field of moving virtual sound sources. Conventional implementations usually reproduce moving virtual sources as a sequence of stationary positions. This process leads to various artifacts as reported in the literature. On the example of wave field synthesis, we show that the explicit consideration of the physical properties of the wave field of moving sources avoids these artifacts and allows for the accurate reproduction of the Doppler Effect. However, numerical simulations suggest that the artifacts inherent to the reproduction system can lead to a heavy degradation of the reproduction quality.
Convention Paper 7363 (Purchase now)

P8-7 A Graphical Tool Set for Analyzing Wave Field Synthesis AlgorithmsThomas Korn, Fraunhofer Institute for Digital Media Technology - Ilmenau, Germany
Current Wave Field Synthesis (WFS) rendering realizations consist of large structures of audio signal processing components (filters, delays, amplitude weighting) that are controlled by complex algorithms based on the virtual source's properties. This paper proposes a set of tools that is used to analyze the underlying WFS coefficient calculation algorithms visually by mapping characteristic measures dependent on the source's and listener's position. These measures are derived from the reproduction system's idealized transfer function and parametric impulse response description. They reveal functional aspects of the algorithm's behavior. The measures aim at supporting an intuitive understanding of the perception of virtual sound events in a Wave Field Synthesis system, but also they facilitate the basic algorithm development process.
Convention Paper 7364 (Purchase now)

Last Updated: 20080612, tendeloo