International Symposium on Room Acoustics
ISRA 2007 SEVILLA
 
Seville, 10 - 12 September 2007
 
Satellite Symposium of the 19th International Congress on Acoustics

ISRA 2007 Sevilla CD-ROM Proceedings

5. Keynote Lecture Abstracts

Graduate School of Engineering, Kobe University; Rokko Nada 657-8501 Kobe, Japan; mrmt_at_or_arroba_kobe-u.ac.jp

Auditory spatial impression is one of the important characteristics perceived in concert halls. The author defines the term auditory spatial impression as the spatial extent of the sound image. Auditory spatial impression comprises at least two components. One is auditory source width (ASW) which is defined as the width of a sound image fused temporally and spatially with the direct (preceding) sound image and the other is listener envelopment (LEV) which is the degree of fullness of sound images around the listener, excluding a sound image composing ASW. A listener can perceive these two components separately. This paper reviews key results of many listening tests on the effects of spatial and temporal structures and spectra of reflections on ASW and LEV by the author.

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KN2

Georgia Tech Lorraine, UMI Georgia Tech – CNRS 2958, Laboratory for Ultrasonic Nondestructive Evaluation, 2 rue Marconi, 57070 Metz-Technopole, France & Georgia Institute of Technology, George W. Woodruff School of Mechanical Engineering, 801 Ferst Drive, Atlanta, GA 30332-0405, USA; nico.declercq_at_or_arroba_me.gatech.edu

The Hellenistic theater of Epidaurus, on the Peloponnese in Greece, attracts thousands of visitors every year who are all amazed by the fact that sound coming from the middle of the theater reaches the outer seats, apparently without too much loss of intensity. The theater, renown for its extraordinary acoustics, is one of the best conserved of its kind in the world. It was used for musical and poetical contests and theatrical performances. The presented numerical study reveals that the seat rows of the theater, unexpectedly play an essential role in the acoustics – at least when the theater is not fully filled with spectators. The seats, which constitute a corrugated surface, serve as an acoustic filter that passes sound coming from the stage at the expense of surrounding acoustic noise. Whether a coincidence or not, the theater of Epidaurus was built with optimized shape and dimensions. Understanding and application of corrugated surfaces as filters rather than merely as diffuse scatterers of sound, may become imperative in the future design of modern theaters. The contents of this paper have been published as Nico F. Declercq, Cindy S. A. Dekeyser, J. Acoust. Soc. Am. 121(4), 2011-2022, 2007. We kindly refer to this paper for more details and for references.

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KN3

DAU; Politecnico di Bari, via Orabona 4, 70125 Bari, Italy; e.cirillo_at_or_arroba_poliba.it; f.martellotta_at_or_arroba_poliba.it

The complex relationships between acoustics and architecture in churches are investigated in this paper. First of all acoustic data collected by the authors in more than fifty Italian churches are compared together with data measured by other researchers in several European churches in order to find similarities and differences with particular reference to reverberation time which is the acoustic parameter most frequently measured. In particular, the dependence of reverberation time as a function of architectural style and volume is investigated in greater detail. The results of this first analysis are then discussed more accurately by taking into account the sample of Italian churches and trying to explain the acoustic behaviour as a function of specific characteristic of each church. Finally, the dependence of other acoustic parameters (such as strength, clarity, and spaciousness) as a function of architectural features is investigated.

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KN4

¹ Graduate Program in Architectural Acoustics, Rensselaer Polytechnic Institute, 110 8th Street, Troy, New York, USA; xiangn_at_or_arroba_rpi.edu
² Naval Research Laboratory, Washington, D.C. 20375-5350, USA; jason.summers_at_or_arroba_nrl.navy.mil

Acoustical designers are increasingly incorporating coupled rooms in performing-arts spaces. Such designs include reverberant secondary rooms coupled to main audience chambers in concert halls and adaptation of opera houses and theatres for concert-hall use via adjustable orchestra shells that couple audience chambers to stage houses. These applications have prompted research on sound fields in coupled-room systems. Having developed an understanding of the possibilities and limitations of statistical-acoustics (SA) predictions, the validity of geometrical-acoustics (GA) modelling tools has been re-examined for the ever-increasing variety of enclosure types. Corrections and improvements are being incorporated into available GA algorithms. Numerical techniques using radiosity and transport theory have also emerged to cope with challenges in prediction of acoustics in coupled-room systems. For validation, physical scale-modelling techniques have become particularly relevant research tools. Despite all of these rapid developments, scientifically grounded analysis methods are still needed for objective and subjective evaluations of sound fields in coupled-room systems, whether in terms of numerical modelling, physical scale modelling, and/or in terms of real-hall measurements. After a brief review of modelling techniques, results are presented of Bayesian decay analysis in characterization of sound-energy decays obtained from numerical modelling and experimental measurements.

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KN5

Institute of Technical Acoustics, RWTH Aachen University, Neustraße 50, 52066 Aachen, Germany; mvo_at_or_arroba_akustik.rwth-aachen.de

The technology for creating a “Virtual Reality”, VR, for wide variety of applications in university and industry has been developed in the last decade. Mostly VR is understood as a tool for 3D visualization, rather than for spatial audio or room acoustics. Nevertheless an important requirement of VR is the multimodal approach which includes vision, sound, tactile and haptic stimuli. The process of creating a physical stimulus based on computer data is called “rendering”. The development of rendering and reproduction of acoustic stimuli in VR is now at a stage where integration of 3D sound is feasible by using PCs. This applies to multi-channel binaural synthesis as well as to full room-acoustic simulation algorithms. In this presentation the requirements of real-time room acoustic simulation are presented.

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KN6

Odeon A/S, c/o Acoustic Technology, Oersted-DTU, Technical University of Denmark, Bldg. 352, DK-2800 Kgs. Lyngby, Denmark; jhr_at_or_arroba_odeon.dk; clc_at_or_arroba_odeon.dk

The application of room acoustic simulations to industrial halls with a large number of sound sources has been known for many years as an efficient means for noise control. However, the application of the auralisation tool to multi-source environments is rather new. The challenges and possibilities are discussed through a number of examples including a symphony orchestra in a concert hall, crowd sounds in a theatre, and the speech privacy in an open plan office. In order to make this technique a useful tool it is important that the quality and realism of the auralisation is very high, but also that the user interface allows a sufficient overview and control of the whole scenario. Good localisation is particularly important in multi-source environments. For some applications the use of headphones is not possible, so it is necessary that the auralisation can be presented through a surround loudspeaker system.

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