AES New York 2009
Paper Session P5

P5 - Virtual Acoustics

Friday, October 9, 2:30 pm — 7:00 pm
Chair: David Griesinger

P5-1 The Effect of Whole-Body Vibration on Preferred Bass Equalization in Automotive Audio Systems—Germain Simon, Chalmers University - Göteborg, Sweden; Sean Olive, Todd Welti, Harman International - Northridge, CA, USA
A set of experiments was conducted to study the effect of whole-body vibration on preferred low frequency equalization of an automotive audio system. Listeners indicated their preferred bass equalization for four different music programs reproduced through a high quality automotive audio system auditioned in situ (in the car) and through a headphone-based binaural room scanning system. The task was repeated while the listener experienced different levels of simulated and real whole-body vibrations associated with the automotive audio system itself. The results reveal that the presence of whole-body vibration can reduce the preferred level of bass equalization by as much as 3 dB depending on the program, the level of vibration, and the individual listener.
Convention Paper 7956 (Purchase now)

P5-2 Using Programmable Graphics Hardware for Acoustics and Audio Rendering—Nicolas Tsingos, Dolby Laboratories - San Francisco, CA, USA
Over the last decade, the architecture of graphics accelerators (GPUs) has dramatically evolved, outpacing traditional general purpose processors (CPUs) with an average 2.25-fold increase in performance every year. With massive processing capabilities and high-level programmability, current GPUs can be leveraged for applications far beyond visual rendering. In this paper we offer an overview of modern programmable GPUs and how they can be applied to acoustics and audio rendering for virtual reality or gaming applications. For tasks ranging from sound synthesis and audio signal processing to numerical acoustic simulations, GPUs massive parallelism and dedicated instructions can offer a 5- to 100-fold performance improvement over traditional CPU implementations. We illustrate such benefits with results from 3-D audio processing and sound scattering simulations and discuss future opportunities for audio and acoustics applications on massively multicore processors.
Convention Paper 7850 (Purchase now)

P5-3 Designing Practical Filters for Sound Field Reconstruction—Mihailo Kolundzija, Christof Faller, Ecole Polytechnique Fédérale de Lausanne - Lausanne, Switzerland; Martin Vetterli, Ecole Polytechnique Fédérale de Lausanne - Lausanne, Switzerland, University of California at Berkeley, Berkeley, CA, USA
Multichannel sound field reproduction techniques, such as Wave Field Synthesis (WFS) and Sound Field Reconstruction (SFR), define loudspeaker filters in the frequency domain. However, in order to use these techniques in practical systems, one needs to convert these frequency-domain characteristics to practical and efficient time-domain digital filters. Additional limitation of SFR comes from the fact that it uses a numerical matrix pseudoinversion procedure, where the obtained filters are sensitive to numerical errors at low levels when the system matrix has high condition number. This paper describes physically-motivated modifications of the SFR approach that allow for mitigating conditioning problems and frequency-domain loudspeaker filter smoothing that allows for designing short time-domain filters without affecting the sound field reconstruction accuracy. It also provides comparisons of sound field reproduction accuracy of WFS and SFR using the obtained discrete-time filters.
Convention Paper 7851 (Purchase now)

P5-4 Investigations on Modeling BRIR Tails with Filtered and Coherence-Matched Noise—Fritz Menzer, Christof Faller, Ecole Polytechnique Fédérale de Lausanne - Lausanne, Switzerland
This paper investigates to what extent the tails of left and right binaural room impulse responses (BRIRs) can be replaced by white Gaussian noise that has been processed to have the same energy decay relief and interaural coherence as the original BRIRs’ tail. For this purpose BRIRs were generated consisting of two parts where the first part is taken from the original BRIR and the second part is filtered and coherence-matched noise. A subjective test was carried out to investigate how the perceived similarity between original and modeled BRIRs decreases as the split point between the parts approaches the direct sound part of the BRIRs. Also, frequency-dependent and conventional frequency-independent interaural coherence matching were compared.
Convention Paper 7852 (Purchase now)

P5-5 Localization of Sound Sources in Reverberant Environments Based on Directional Audio Coding Parameters—Oliver Thiergart, Richard Schultz-Amling, Giovanni Del Galdo, Dirk Mahne, Fabian Kuech, Fraunhofer Institute for Integrated Circuits IIS - Erlangen, Germany
Methods for spatial audio processing are becoming more important as the variety of multichannel audio applications is permanently increasing. Directional Audio Coding (DirAC) represents a well proven technique to capture and reproduce spatial sound on the basis of a downmix audio signal and parametric side information, namely direction of arrival and diffuseness of the sound. In addition to spatial audio reproduction, the DirAC parameters can be exploited further. In this paper we propose a computationally efficient approach to determine the position of sound sources based on DirAC parameters. It is shown that the proposed localization method provides reliable estimates even in reverberant environments. The approach also allows to trade off between localization accuracy and tracking performance of moving sound sources.
Convention Paper 7853 (Purchase now)

P5-6 Distance Perception in Loudspeaker-Based Room Auralization —Sylvain Favrot, Jörg M. Buchholz, Technical University of Denmark - Kgs. Lyngby, Denmark
A loudspeaker-based room auralization (LoRA) system has been recently proposed that efficiently combines modern room acoustic modeling techniques with high-order Ambisonics (HOA) auralization to generate virtual auditory environments (VAEs). The reproduction of the distance of sound events in such VAE is very important for its fidelity. A direct-scaling distance perception experiment was conducted to evaluate the LoRA system including the use of near-field control (NFC) for HOA. Experimental results showed that (i) loudspeaker-based auralization in the LoRA system provides similar distance perception to that of the corresponding real environment and that (ii) NFC-HOA provides a significant increase in the range of perceived distances for near sound sources as compared to standard HOA.
Convention Paper 7854 (Purchase now)

P5-7 Dual Radius Spherical Cardioid Microphone Arrays for Binaural Auralization—Frank Melchior, IOSONO GmbH - Erfurt, Germany, TU Delft, Delft, The Netherlands; Oliver Thiergart, Giovanni Del Galdo, Fraunhofer Institute for Integrated Circuits IIS - Erlangen, Germany; Diemer de Vries, TU Delft - Delft, The Netherlands; Sandra Brix, Fraunhofer IDMT - Ilmenau, Germany
The direction dependent analysis of impulse response measurements using spherical microphone arrays can deliver a universal basis for binaural auralization. A new method using dual radius open sphere arrays is proposed to overcome limitations in practical realizations of such arrays. Different methods to combine the two radii have been analyzed and will be presented. A plane wave decomposition in conjunction with a high resolution HRTF database is used to generate a binaural auralization, wherein the different designs are simulated under ideal and real conditions. The results have been evaluated in a quality grading experiment. It is shown that the dual radius cardioids design is an effective method to enhance the perceived quality in comparison to conventional spherical array designs.
Convention Paper 7855 (Purchase now)

P5-8 Recording Multichannel Sound within Virtual Acoustics—Wieslaw Woszczyk, Tom Beghin, Martha de Francisco, Doyuen Ko, McGill University - Montreal, Quebec, Canada
Virtual acoustic environments were implemented in a laboratory based on real-time convolution of multiple high-resolution impulse responses previously measured in real rooms. The quality of these environments has been tested during live music performance and recording in a highly demanding Virtual Haydn Project. The technological and conceptual novelty of this project is to allow one to separate the recording of the direct sound and of the ambient sound into two independent processes, each individually optimized and adjusted. The method offers recording and rehearsal rooms that are guaranteed to be quiet and free from traffic noise and other interference. At present, the technical complexity and system cost are still very high but we can expect that these will be reduced in time.
Convention Paper 7856 (Purchase now)

P5-9 The Application of Compressive Sampling to the Analysis and Synthesis of Spatial Sound Fields—Nicolas Epain, Craig Jin, André Van Schaik, University of Sydney - Sydney, NSW, Australia
Compressive sampling provides a new and interesting tool to optimize measurements of physical phenomena with a small number of sensors. The essential idea is that close to perfect reconstruction of the observed phenomenon may be possible when it can be described by a sparse set of basis functions. In this paper we show how to apply compressive sampling techniques to the recording, analysis, and synthesis of spatially extended sound fields. Numerical simulations demonstrate that our proposed method can dramatically improve the playback of spatialized sound fields as compared, for example, with High Order Ambisonics.
Convention Paper 7857 (Purchase now)