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AES Munich 2009
Paper Session P21

P21 - Spatial Rendering–Part 2

Saturday, May 9, 15:00 — 18:30
Chair: Sascha Spors, Technical University of Berlin - Berlin, Germany

P21-1 Score File Generators for Boids-Based Granular Synthesis in CsoundEnda Bates, Dermot Furlong, Trinity College - Dublin, Ireland
In this paper we present a set of score file generators and granular synthesis instruments for the Csound language. The applications use spatial data generated by the Boids flocking algorithm along with various user-defined values to generate score files for grainlet additive synthesis, granulation, and glisson synthesis instruments. Spatialization is accomplished using Higher Order Ambisonics and distance effects are modeled using the Doppler Effect, early reflections, and global reverberation. The sonic quality of each synthesis method is assessed and an original composition by the author is presented.
Convention Paper 7761 (Purchase now)

P21-2 Acoustical Rendering of an Interior Space Using the Holographically Designed Sound ArrayWan-Ho Cho, Jeong-Guon Ih, KAIST - Daejeon, Korea
It was reported that the filter for the acoustic array can be inversely designed in a holographic way, which was demonstrated in a free-field. In this study the same method using the boundary element method (BEM) was employed to render the interior sound field in an acoustically desired fashion. Because the inverse BEM technique can deal with arbitrary shaped source or bounding surfaces, one can simultaneously consider the effect of irregular radiation surface and reflection boundaries having impedances such as walls, floor, and ceiling. To examine the applicability, a field rendering example was tested to control the relative spatial distribution of sound pressure in the enclosed field.
Convention Paper 7762 (Purchase now)

P21-3 Validation of a Loudspeaker-Based Room Auralization System Using Speech Intelligibility MeasuresSylvain Favrot, Jörg M. Buchholz, Technical University of Denmark - Lyngby, Denmark
A novel loudspeaker-based room auralization (LoRA) system has been proposed to generate versatile and realistic virtual auditory environments (VAEs) for investigating human auditory perception. This system efficiently combines modern room acoustic models with loudspeaker auralization using either single loudspeaker or high-order Ambisonics (HOA) auralization. The LoRA signal processing of the direct sound and the early reflections was investigated by measuring the speech intelligibility enhancement by early reflections in diffuse background noise. Danish sentences were simulated in a classroom and the direct sound and each early reflection were either auralized with a single loudspeaker, HOA or first-order Ambisonics. Results indicated that (i) absolute intelligibility scores are significantly dependent on the reproduced technique and that (ii) early reflections reproduced with HOA provide a similar benefit on intelligibility as when reproduced with a single loudspeaker. It is concluded that speech intelligibility experiments can be carried out with the LoRA system either with the single loudspeaker or HOA technique.
Convention Paper 7763 (Purchase now)

P21-4 Low Complexity Directional Sound Sources for Finite Difference Time Domain Room Acoustic ModelsAlexander Southern, Damian Murphy, University of York - York, UK
The demand for more natural and realistic auralization has resulted in a number of approaches to the time domain implementation of directional sound sources in wave-based acoustic modeling schemes such as the Finite Difference Time Domain (FDTD) method and the Digital Waveguide Mesh (DWM). This paper discusses an approach for implementing simple regular directive sound sources using multiple monopole excitations with distributed spatial positioning. These arrangements are tested along with a discussion of the characteristic limitations for each setup scenario.
Convention Paper 7764 (Purchase now)

P21-5 Binaural Reverberation Using a Modified Jot Reverberator with Frequency-Dependent and Interaural Coherence MatchingFritz Menzer, Christof Faller, Ecole Polytechnique Fédérale de Lausanne - Lausanne, Switzerland
An extension of the Jot reverberator is presented, producing binaural late reverberation where the interaural coherence can be controlled as a function of frequency such that it matches the frequency-dependent interaural coherence of a reference binaural room impulse response (BRIR). The control of the interaural coherence is implemented using linear filters outside the reverberator’s recursive loop. In the absence of a reference BRIR, these filters can be calculated from an HRTF set.
Convention Paper 7765 (Purchase now)

P21-6 Design and Limitations of Non-Coincidence Correction Filters for Soundfield MicrophonesChristof Faller, Illusonic LLC - Lausanne, Switzerland; Mihailo Kolundzija, Ecole Polytechnique Fédérale de Lausanne - Lausanne, Switzerland
The tetrahedral microphone capsule arrangement in a soundfield microphone captures a so-called A-format signal, which is then converted to a corresponding B-format signal. The phase differences between the A-format signal channels due to non-coincidence of the microphone capsules cause coloration and errors in the corresponding B-format signals and linear combinations thereof. Various strategies for designing B-format non-coincidence correction filters are compared and limitations are discussed.
Convention Paper 7766 (Purchase now)

P21-7 Generalized Multiple Sweep MeasurementStefan Weinzieri, Andre Giese, Alexander Lindau, TU Berlin - Berlin, Germany
A system identification by impulse response measurements with multiple sound source configurations can benefit greatly from time-efficient measurement procedures. An optimized method by interleaving and overlapping of multiple exponential sweeps (MESM) used as excitation signals was presented by Majdak et al. (2007). For single system identifications, however, much higher signal-to-noise ratios (SNR) can be reached with sweeps whose magnitude spectra are adapted to the background noise spectrum of the acoustical environment, as proposed by Müller & Massarani (2001). We investigated on which conditions and to what extent the efficiency of multiple sweep measurements can be increased by using arbitrary, spectrally adapted sweeps. An extension of the MESM approach toward generalized sweep spectra is presented, along with a recommended measurement procedure and a prediction of the efficiency of multiple sweep measurements depending on typical measurement conditions.
Convention Paper 7767 (Purchase now)