AES Rome 2013
Paper Session P18

P18 - Spatial Audio—Part 3: Ambisonics, WFS

Tuesday, May 7, 14:30 — 16:30 (Sala Carducci)

Symeon Delikaris-Manias, Aalto University - Helsinki, Finland

P18-1 An Ambisonics Decoder for Irregular 3-D Loudspeaker ArraysDaniel Arteaga, Fundacio Barcelona Media - Barcelona, Spain; Universitat Pompeu Fabra - Barcelona, Spain
We report on the practical implementation of an Ambisonics decoder for irregular 3-D loudspeaker layouts. The developed decoder, which uses a non-linear search algorithm to look for the optimal Ambisonics coefficients for each loudspeaker, has a number of features specially tailored for reproduction in real-world 3-D audio venues (for example, special 3-D audio installations, concert halls, audiovisual installations in museums, etc.). In particular, it performs well even for highly irregular speaker arrays, giving an acceptable listening experience over a large audience area.
Convention Paper 8918 (Purchase now)

P18-2 The Effect of Low Frequency Reflections on Stereo ImagesJamie A. S. Angus, University of Salford - Salford, Greater Manchester, UK
This paper looks at the amount of absorption required to adequately control early reflections in reflection-controlled environments at low frequencies (< 700 Hz). This is where the Inter-aural Time Delay Cue (ITD) is important. Most work has focused on wideband energy time performance. In particular, it will derive the effect a given angle and strength of reflection has on the phantom image location using the Blumlein equations. These allow the effect of reflections as a function of frequency to be quantified. It will show that the effect of reflections are comparatively small for floor and ceiling reflections, but that lateral reflections depend on the phantom image location and get worse the more off-center the phantom image becomes.
Convention Paper 8919 (Purchase now)

P18-3 Parametric Spatial Audio Reproduction with Higher-Order B-Format Microphone InputVille Pulkki, Aalto University - Aalto, Finland; Archontis Politis, Aalto University - Espoo, Finland; Giovanni Del Galdo, Ilmenau University of Technology - Ilmenau, Germany; Achim Kuntz, Fraunhofer Institute for Integrated Circuits IIS - Erlangen, Germany
A time-frequency-domain non-linear parametric method for spatial audio processing is presented here, which can utilize microphone input having directional patterns of any order. The method is based on dividing the sound field into overlapping or non-overlapping sectors. Local pressure and velocity signals are measured within each sector, and an individual Directional Audio Coding (DirAC) processing is performed for each sector. It is shown, that in certain acoustically complex conditions the sector-based processing enhances the quality compared to traditional first-order DirAC processing.
Convention Paper 8920 (Purchase now)

P18-4 Wave Field Synthesis of Virtual Sound Sources with Axisymmetric Radiation Pattern Using a Planar Loudspeaker ArrayFilippo Maria Fazi, University of Southampton - Southampton, Hampshire, UK; Ferdinando Olivieri, University of Southampton - Southampton, Hampshire, UK; Thibaut Carpentier, UMR STMS IRCAM-CNRS-UPMC - Paris, France; Markus Noisternig, UMR STMS IRCAM-CNRS-UPMC - Paris, France
A number of methods have been proposed for the application of Wave Field Synthesis to the reproduction of sound fields generated by point sources that exhibit a directional radiation pattern. However, a straightforward implementation of these solutions involves a large number of real-time operations that may lead to very high computational load. This paper proposes a simplified method to synthesize virtual sources with axisymmetric radiation patterns using a planar loudspeaker array. The proposed simplification relies on the symmetry of the virtual source radiation pattern and on the far-field approximation, although a near-field formula is also derived. The mathematical derivation of the method is presented and numerical simulations validate the theoretical results.
Convention Paper 8921 (Purchase now)

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