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AES Barcelona 2005
Paper Session H - Room and Architectural Acoustics & Sound Reinforcement

Last Updated: 20050405, mei

Sunday, May 29, 14:00 — 18:00

Chair: Manuel Sobreira

H-1 First Approach to Combine Particle Model Algorithms with Modal Analysis Using FEMMahesh Bansal, Technical University - Berlin, Germany; Stefan Feistel, SDA Software Design Ahnert - Berlin, Germany; Wolfgang Ahnert, ADA Acoustic Design Ahnert - Berlin, Germany
Geometrical approaches, like ray tracing methods and image source methods, are not sufficient in small and complex shaped rooms in order to take proper account of the wave nature of the sound field and to obtain room acoustic characteristics in higher quality in the low frequency bands. We present an overview of using the Finite Element Method (FEM) for performing modal analysis in closed environments and to show diffraction effects in EASE, the acoustic simulation software, which is not possible with existing particle models especially below the Schroeder frequency. For this purpose we consider the solution of the general quadratic eigenvalue problem arising from finite element analysis in enclosures with complex shapes and general impedance boundary condition. We are mainly concerned with the attempt of showing the practical feasibility of FEM in room acoustics and to combine it with the particle model in order to obtain the broad-band response of the room. Also, fundamental points regarding the Finite Element Method, iterative methods, and required mesh quality are discussed.
Convention Paper 6392 (Purchase now)

H-2 Bayesian Probabilistic Analysis of Sound Energy Decay Characteristics in Acoustically Coupled RoomsNing Xiang, Mendel Kleiner, Rensselaer Polytechnic Institute - Troy, NY; Paul Goggans, University of Mississippi - University, MS, USA
One of tasks in analyzing acoustics of coupled spaces is to evaluate different decay times from double-slope decay characteristics of Schroeder decay functions using measured room impulse responses. Traditionally, however, identification of double- or multiple-sloped decay in room impulse response measurement has been considered very challenging. We apply Bayesian probabilistic analysis methods to cope with the demanding tasks in estimating multiple decay times from Schroeder decay functions. Using experimentally measured data in real coupled spaces, this paper discusses estimation of decay times and related parameters within Bayesian framework.
Convention Paper 6393 (Purchase now)

H-3 Digital Waveguide Networks for Room Response Modeling and SynthesisMatti Karjalainen, Helsinki University of Technology - Espoo, Finland; Patty Huang, Stanford University - Stanford, CA, USA, and Helsinki University of Technology, Espoo, Finland; Julius O. Smith III, Stanford University - Stanford, CA, USA
Digital waveguide networks (DWN) are known as a methodology to simulate spatially distributed systems, such as reverberators (room simulation) and resonators of musical instruments. This paper is a study on the application of DWNs to simulate acoustic spaces for room rendering, including binaural auralization. The methods discussed combine the principles of digital waveguide meshes, image source models, reverberation algorithms, and HRTF-based rendering. Examples are given on synthesizing binaural room responses for simple room geometries, and the possibilities of fitting the models to given real room responses is discussed. System performance is analyzed from the point of view of real-time virtual acoustics.
Convention Paper 6394 (Purchase now)

H-4 Evaluation of Artificial Reverberation Decay QualityPer Rubak, Aalborg University - Aalborg, Denmark
Three different methods to evaluate artificial reverberation decay quality are investigated (monaural attributes). The first method is based on evaluation of the autocorrelation function Φ(τ) in octave bands. The temporal diffusion, defined by Kuttruff as Δ = Φ(0)/ max {Φ(τ ≠ 0)}, is proposed as a simple engineering metric. The second method employ evaluation of the short time energy in the impulse response filtered in octave bands. A sliding 30 ms window was employed to calculate the short time energy in the filtered room impulse responses (exponential decay was compensated by an exponential increasing factor). The last method was a modified version of the Kohlrausch spectral stationarity test called Reverb-prints.
Convention Paper 6395 (Purchase now)

H-5 Acoustical Simulation and Auralization in MosquesWasim Orfali, Technical University of Berlin - Berlin, Germany; Wolfgang Ahnert, ADA Acoustic Design Ahnert - Berlin, Germany
Compared to churches, no appreciable amount of work has been done in evaluating the acoustical parameters of mosques. The present paper deals with acoustic computer simulations and in particular with comparing measured room-acoustical parameters and those obtained by calculation in a computer model. Afterward, models of former mosques were created and sound restoration for such mosques by means of an auralization tool will be part of the main objective of this paper. Two historical mosques which do not exist anymore, but are well known in literature will be modeled and sound auralization will be performed to demonstrate what kind of acoustic conditions prevailed inside these mosques and how the two mosques sounded in their time.
Convention Paper 6396 (Purchase now)

H-6 Active Diffusers: Stability Analysis and Multiple Active ElementsMark R. Avis, The University of Salford - Salford, UK; Lejun Xiao, The University of Birmingham - Birmingham, UK; Trevor Cox, The University of Salford - Salford, UK
This paper presents some results concerning active diffusers. In particular it addresses the issues of stability, sensitivity to impedance errors, and the use of multiple active elements. The stability of an impedance controller used to virtually extend diffuser wells is theoretically analyzed based on a practically measured plant model. The analysis is extended to diffusers with multiple active elements empirically. A sensitivity analysis shows that the control impedance must be achieved quite precisely with active diffusers, and the error sensitivity varies with frequency. Measurements on an active diffuser with multiple elements show that the scattering performance of the active diffuser is comparable to its passive equivalent, while the active solution requires less space.
Convention Paper 6397 (Purchase now)

H-7 Acoustic Design with Textile Absorbers and FoilsBernd Schumann, Thomas Görne, Detmold University of Music - Detmold, Germany
Rooms used for remote recordings or live stages are sometimes acoustically inappropriate for other purposes, e.g., when working in churches or industrial venues. This paper describes simple and cost-effective solutions for acoustic optimization of highly reverberant rooms by means of mobile and easy-to-get materials. Absorption coefficients of materials like blankets or tarpaulins are measured and compared with theater decoration materials and professional acoustic fabrics. Special arrangements of "on-the-fly" absorbers are tested.
Convention Paper 6398 (Purchase now)

H-8 Is STIPa a Robust Measure of Speech Intelligibility Performance?Peter Mapp, Peter Mapp Associates - Colchester, UK
STIPa (STI for PA systems) is rapidly becoming a popular method of assessing speech intelligibility. It was conceived in order to overcome the problems associated with RaSTI when measuring the potential intelligibility performance of a sound system. The paper reports the results of extensive testing carried out on a variety of sound systems and controlled test environments using measurement equipment from four different manufacturers. It is concluded, that while theoretically, STIPa should be able to accurately predict STI, in practice, actually realizing this goal may not be quite so straightforward. A number of error mechanisms were found and are reported together with estimations of the typical measurement accuracy and repeatability that can be expected when undertaking STI performance testing.
Convention Paper 6399 (Purchase now)

©2005 Audio Engineering Society, Inc.