AES London 2010
Paper Session P2

P2 - Sound Reinforcement and Room Acoustics

Saturday, May 22, 09:30 — 12:30 (Room C5)
Chair: Glenn Leembruggen, Acoustic Directions Pty Ltd. - ICE Design, Sydney, Australia, and University of Sydney, Sydney, Australia

P2-1 Simultaneous Soundfield Reproduction at Multiple Spatial Regions—Yan Jennifer Wu, Thushara D. Abhayapala, The Australian National University - Canberra, Australia
Reproduction of different sound fields simultaneously at multiple spatial regions is a complex problem in acoustic signal processing. In this paper we present a framework to recreate 2-D sound fields simultaneously at multiple spatial regions using a single loudspeakers array. We propose a novel method of finding an equivalent global sound field that consists of each individual desired sound field by the spatial harmonic coefficients translation between the coordinate systems. This method makes full use of the available dimensionality of the sound field. Some fundamental limits are also revealed. Specifically, the number of spatial regions could be reproduced inside the single loudspeaker array as determined by the total dimensionality from each sound field.
Convention Paper 7967 (Purchase now)

P2-2 Verification of Geometric Acoustics-Based Auralization Using Room Acoustics Measurement Techniques—Aglaia Foteinou, Damian Murphy, University of York - Heslington, UK; Anthony Masinton, University of York - King’s Manor, York, UK
Geometric acoustics techniques such as ray-tracing, image-source, and variants are commonly used in the simulation and auralization of the acoustics of an enclosed space. The shortcomings of such techniques are well documented and yet they are still the methods most commonly used and accepted in architectural acoustic design. This work compares impulse response-based objective acoustic measures obtained from a 3-D model of a medieval English church using a combination of image-source and ray-tracing geometric acoustic methods, with measurements obtained within the actual space. The results are presented in both objective and subjective terms, and include an exploration of optimized boundary materials and source directivity characteristics with problems and limitations clarified.
Convention Paper 7968 (Purchase now)

P2-3 Analysis Tool Development for the Investigation of Low Frequency Room Acoustics by Means of Finite Element Method—Christos Sevastiadis, George Kalliris, George Papanikolaou, Aristotle University of Thessaloniki - Thessaloniki, Greece
The sound wave behavior at low frequencies in small sound recording, control, and reproduction rooms, results in resonant sound fields observed in both frequency and spatial domains. Finite Element Method (FEM) software applications provide potential analysis procedures for acoustics problems but there is a lack of tools focusing on room acoustics investigation. The present paper is the result of an attempt to develop a room acoustics modeling tool integrated with a FEM. Simple room construction, common acoustical treatments, and multiple source excitations are involved in modal and steady state analysis procedures in order to simplify the solution of problematic sound fields. The key parameters and features, as long as validation experimental results are presented.
Convention Paper 7969 (Purchase now)

P2-4 Subwoofers in Rooms: Experimental Modal Analysis—Juha Backman, Nokia Corporation - Espoo Finland
The behavior of a loudspeaker in a room depends fully on the coupling of the loudspeaker to the room modes, which are in the subwoofer frequency range individually identifiable. The modes can be determined through computational methods if the surface properties and room geometry are simple enough, but systems with complex properties have to be analyzed experimentally. The paper describes the use of modal analysis techniques, usually applied only to two-dimensional structures, for three-dimensional spaces to determine experimentally the actual modes and their properties.
Convention Paper 7970 (Purchase now)

P2-5 Subwoofer Positioning, Orientation, and Calibration for Large-Scale Sound Reinforcement—Adam Hill, Malcolm Hawksford, University of Essex - Colchester, UK; Adam P. Rosenthal, Gary Gand, Gand Concert Sound - Glenview, IL, USA
It is often difficult to achieve even coverage at low-frequencies across a large audience area. To complicate matters, it is desirable to have tight control of the low-frequency levels on the stage. This is generally dealt with by using cardioid subwoofers. While this helps control the stage area, the audience area receives no clear benefit. This paper investigates how careful positioning, orientation, and calibration of a multiple subwoofer system can provide enhanced low-frequency coverage, both in the audience area and on the stage. The effects of placement underneath, on top of, and in front of the stage are investigated as well as the performance of systems consisting of both flown and ground-based subwoofers.
Convention Paper 7971 (Purchase now)

P2-6 Live Measurements of Ground-Stacked Subwoofers' Performance—Elena Shabalina, Mathias Kaiser, RWTH Aachen University - Aachen, Germany; Janko Ramuscak, d&b audiotechnik GmbH - Backnang, Germany
Various software-based measurement systems can be used for live sound measurements with music or speech signals in occupied concert halls with sufficient accuracy. However for some special applications as measuring the performance of a ground-stacked bass array component of a multiple component sound reinforcement system in an occupied hall, these systems cannot be used directly, since it is not possible to run a bass array alone during a concert. A simple method to obtain the subwoofers' impulse response using program signal measurements of a full range PA system is proposed. The desired impulse response results from subtraction of full system impulse responses with and without subwoofers running. Required measurement conditions and limitations are discussed.
Convention Paper 7972 (Purchase now)