Wave Field Synthesis

Wave Field Synthesis can dramatically increase the quality of sound reproduction. To create new vir- tual rooms with realistic ambience within any listen- ing space, new ideas for room simulation and virtual acoustics are needed. The work originally started at Delft Technical University (TU Delft) is now contin- ued at a number of research locations. The paper will introduce the

In this paper we present a technique for the rendering
of directional sources by means of loudspeaker arrays.
The proposed methodology is based on a decomposition of the sound field in terms of plane waves. Within this framework the directivity of the source is naturally included in the rendering problem, therefore accommodating the directivity into the picture becomes much simpler. For this purpose, the loudspeaker array is subdivided into overlapping sub-arrays, each generating a plane
wave component. The individual plane waves are then weighed by the desired directivity pattern. Simulations and experimental results show that the proposed technique is able to reproduce the sound field of directional sources with an improved accuracy with respect to existing techniques.

Common room compensation algorithms are capable of dereverberating the listening room at some discrete points only. Outside these equalization points the sound quality is often even worse compared to the unequalized case. As wave field synthesis in principle allows to control the wave field within the listening area it can also be used to compensate for the reflections caused by

Spatial Audio Perception and Envelopment are key areas of investigation for understanding audience attention and engagement when experiencing works through loudspeakers sound diffusion systems. This paper reports about the findings of a practice-based interdisciplinary research study on the perception of movement through sound realised at the Unit of Sound Practice Research at the Goldsmiths University of London, in collaboration with Trinity Laban Conservatory of Music and Dance, Mondriaan Foundation, and The Game of Life Foundation (NL). The project consists in a joint choreography of sound and body movement, designed and performed through the 192 Loudspeakers Wave Field Synthesis System by The Game of Life Foundation, premiered in Den Haag (NL) and at the London's First International Symposium on Sound and Movement Practices in 2014. The ideas and examples discussed are focussed on multimodality and audiovisual perception, exploring the involved modalities in movement perception and how they could be integrated in a spatial audio composition for dance. The findings of this investigation inform the context of auditory engagement and attention with the perspectives of a composer and choreographer involved in answering perceptual questions as part of their artistic practice.

The aim of the proposed system is to create an immersive audio environment for desktop applications without using headphones. It allows the spatialisation of 3D sound fields around an almost free mobile listener. The sound field is reproduced by a several loudspeakers positioned along the desktop edges without using head tracking. Loudspeaker driving signals are derived by combining the Holographic

We present a new software system for spatial audio repro- duction called SoundScape Renderer. It is currently used for rendering 2-dimensional virtual acoustic scenes using either Wave Field Synthesis, binaural rendering or Vector Based Amplitude Panning. A further extension to higher order Am- bisonics is planned. However, in this paper we will focus on the WFS functionality. We also describe the physical setup of the WFS system in- stalled at the Usability Laboratory of Deutsche Telekom Lab- oratories, the natural habitat of the SoundScape Renderer. Finally, we present a working draft for an XML file for- mat enabling the exchange of acoustic scenes between differ- ent software systems. This Audio Scene Description Format (ASDF) is entirely open and we encourage everyone to par- ticipate in its further definition.

Abstract. A practice-based project that explores design theories of spatial music with choreographic concepts and practices. Aspects of Wave Field Synthesis and Ambisonics technologies are discussed. A production of original works for dance and music in surround sound constitutes the expected outcomes.

A method to synthesize the sound radiation characteristics of musical instruments in a wave front synthesis system is proposed and tested. Radiation patterns of a violin are measured with a circular microphone array which consists of 128 pressure receivers. For each critical frequency band one exemplary radiation pattern is decomposed to circular harmonics of order 0 to 64. So the radiation characteristic of the violin is represented by 25 complex radiation patterns. On the reproduction side, these circular harmonics are approximated by 128 densely spaced monopoles by means of 128 broadband impulses. An anechoic violin recording is convolved with these impulses, yielding 128 filtered versions of the recording. These are then synthesized as 128 monopole sources in a wave front synthesis system and compared to a virtual monopole playing the unfiltered recording. The subjects perceive the tone color of the recreated virtual violin as being dependent on the listening position and report that the two source types have a different “presence.” The test persons rate the virtual violin as less natural, sometimes remarking that the filtering is audible at high frequencies. Further studies with a denser spacing of the virtual monopoles and a presentation in an anechoic room are planned.

Current approaches for active noise control in large listening spaces require a high number of sensors to control the sound field within a given volume. This contribution presents a new approach based on the theory of acoustic wave propagation. It exploits the fact, that a distribution of sources and sensors on the boundary of the listening space is sufficient for global control of the enclosed field. This principle has already been successfully exploited for spatial audio reproduction and is now applied to active noise control. Theoretical considera- tions, simulations, and measurements with a wave field syn- thesis array show that this approach is capable of consider- able noise reduction in low-reverberant enclosures. Exten- sions to listening spaces with higher reverberation times are straightforward but require an increased number of output channels.

Multiactuator Panels (MAPs) are flat loudspeakers that can be used to build arrays for Wave Field Synthesis (WFS), al- ternatively to classical dynamic loudspeakers. The sound ra- diation of these loudspeakers is a complex superposition of excited modes that vary strongly with frequency. Therefore, the characteristic MAP spectrum is very irregular and needs to be equalized to obtain a flat,

The application of adaptive algorithms like noise reduction or echo cancellation on Wave Field Synthesis and Wave Field Analysis may be performed by using Wave Domain Adaptive Filtering in order to limit the computational complexity. The computational cost can be furthermore reduced taking advantage of filter banks theory. Moreover, the signal decomposition into subbands allows to achieve a faster convergence rate and a lower mean-square error for these adaptive algorithms. In this paper we introduce a ...

Common room compensation algorithms are capable of dereverberating the listening room at some discrete points only. Outside of these equalization points the sound quality is often even worse compared to the unequalized case. However a new rendering technique - wave field synthesis - allows to control the wave field within the listening area. Therefore it can also be used to

In this paper a psychoacoustic sound field synthesis (pSFS) system for musical applications is presented. It recreates the radiation patterns of musical instruments
for an extended listening area. For this purpose several psychoacoustic effects are utilized: Considering the critical bandwidth, the amount of data to be processed can be
reduced massively. Applying a "precedence fade" allows for wave fronts to arrive from angles opposing to the virtual source position when regarding the integration time
of the auditory system and phenomenons known from the field of auditory scene analysis. A listening test demonstrates that the approach results in a precise source localization together with a spatial sound impression which is known to be the most crucial aspect of the subjective acoustical quality of concert halls. This is achieved even in a reverberant room and with a relatively large distance between loudspeakers compared to other wave field synthesis systems. Implementations in audio systems such as 5.1 or wave field synthesis systems with a large number of loudspeakers are possible.

Defining space is one of the essential elements of architectural design, merging perception with certain programmatic functions. From a tangible and tectonic point of view, space usually forms a three-dimensional framework. Since Albert Einstein, however, time has brought added complexity to the space-time relation. The concept of space needs revising in order to address nonlinear time, as well as the intangible computer-mediated layer we now find in everyday life. Physical three-dimensional space is expanded by several technological layers, producing hybridizations with other fields of knowledge. Computerized two-dimensional interfaces, such as applications or programs, establish a space that is formless but has an added temporal dimension. Examples of this new type of medium are complex digital and immersive spaces, such as intangible, virtual, augmented, locative and telecommunication spaces. In Wave Field Synthesis techniques, sound directly, physically articulates space, albeit by means of highly complex digital calculations carried out by a computer cluster and an array of speakers. The inclusion of sound as a parameter in the design process enables the use of sound to indirectly shape space in a more algorithmic, procedural way.
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Sound field synthesis approaches aim at creating a desired sound field. Conventionally, these approaches are physically-motivated. Acoustical properties define the desired sound field. A perceptual evaluations of the listening experience follows the technical implementation. Psychoacoustic sound field synthesis, as introduced in this chapter, has another paradigm. Here, psychoacoustical properties determine the desired sound field. This allows for implementation of auditory  thresholds and integration times in the derivation of the sound field synthesis core. This allows for inaudible reduction of temporal, spatial, and spectral resolution. The result is a natural, spatial listening experience and a precise source localization for multiple listeners with comparably low computational efforts and inaudible synthesis errors.