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P15 - Room and Architectural AcousticsMonday, May 22, 08:40 — 12:00
Chair: Jan Voetmann, DELTA Acoustics - Hoersholm, Denmark
P15-1 Koch’s Snowflake: A Case Study of Sound Scattering of Fractal Surfaces—David Degos, Steven Edson, Densil Cabrera, University of Sydney - Syndey, New South Wales, Australia
Diffusion and scattering are becoming increasingly relevant in room acoustics design. The scattering performance of current passive diffusers is often restricted to a certain bandwidth due to physical constraints. One possible approach to this is to use fractal surface profiles, which have similar geometric features over a wide range of scales, and so should achieve an extended bandwidth for effective scattering. A range of acoustic panels of varying complexity, based around Koch’s Snowflake pattern, was constructed and tested using a two-dimensional pseudo-anechoic method adapted from the AES-4id-2001. This paper reports on these results and also on issues encountered in implementing the measurements.
[Associated Poster Presentation in Session P21, Monday, May 22, at 14:00]
Presentation is scheduled to begin at 08:40
Convention Paper 6735 (Purchase now)
P15-2 Large Scale FEM Analysis of a Studio Room—Mahesh Bansal, Technical University of Berlin - Berlin, Germany; Stefan Feistel, SDA, Software Design Ahnert - Berlin, Germany; Wolfgang Ahnert, ADA, Acoustic Design Ahnert - Berlin, Germany
In room acoustics, particle models like ray tracing and image source method are not sufficient to explain the wave nature especially at low frequencies. For detailed acoustic investigation, many wave-based approaches like FEM, BEM, and finite difference methods have been proposed. We present an application of large-scale FEM analysis in order to obtain eigenmodes and transfer functions of a real-world studio with general impedance boundary conditions. Since FEM needs discretization of geometry into small elements like tetrahedral and hexahedral, we also propose a novel all-hexahedral mesh generator for arbitrary shaped rooms and show its application in room acoustics.
Presentation is scheduled to begin at 09:00
Convention Paper 6736 (Purchase now)
P15-3 Influence of Ray Angle of Incidence and Complex Reflection Factor on Acoustical Simulation Results (Part II)—Emad El-Saghir, Acoustic Design Ahnert Limited - Cairo, Egypt; Stefan Feistel, SDA Software Design Ahnert GmbH - Berlin, Germany
In a previous paper (Convention Paper 6171, 116th AES Convention, Berlin, Germany), it was shown that the influence of neglecting the incidence-angle dependence of absorption coefficients in a simple single-source shoebox room model was insignificant as far as simulation results are concerned. Neglecting phase shift at each reflection led, however, to a significant difference in the predicted pressure in the same model. This paper investigates the same two questions in a complicated model with several sources and a diversity of surface materials. It attempts to analytically estimate the error associated with disregarding these two issues.
[Associated Poster Presentation in Session P21, Monday, May 22, at 14:00]
Presentation is scheduled to begin at 09:20
Convention Paper 6737 (Purchase now)
P15-4 Adaptive Audio Equalization of Rooms Based on a Technique of Transparent Insertion of Acoustic Probe Signals—Ariel Rocha, António Leite, Francisco Pinto, Aníbal Ferreira, University of Porto - Porto, Portugal
This paper presents a new method of performing real time adaptive equalization of room acoustics in the frequency domain. The developed method obtains the frequency response of the room by means of transparent insertion of a certain number of acoustic probe signals into the main audio spectrum. The opportunities for the insertion of tones are identified by means of a spectral analysis of the audio signal and using a psychoacoustic model of frequency masking. This enhanced version of the adaptive equalizer will be explained as well as its real-time implementation on a TMS320C6713 DSP-based platform. Results of the acoustic tests and conclusions about its performance will be presented.
[Associated Poster Presentation in Session P21, Monday, May 22, at 14:00]
Presentation is scheduled to begin at 09:40
Convention Paper 6738 (Purchase now)
P15-5 An Amphitheatric Hall Modal Analysis Using the Finite Element Method Compared to In Situ Measurements—Anastasia Papastefanou, Christos Sevastiadis, George Kalliris, George Papanikolaou, Aristotle University of Thessaloniki - Thessaloniki, Greece
The distribution of the low frequency room modes is important in room acoustics. The Finite Element Method (FEM) is a powerful numerical technique for analyzing the behavior of sound waves in enclosures, especially irregular ones. Also, it is the method that produces reliable results in the low frequency range where other methods like ray tracing and image source methods fail. A modal analysis is presented using the FEM in a nonrectangular, medium-sized amphitheatric hall, and we compare the calculated results with those obtained by on site measurements.
[Associated Poster Presentation in Session P21, Monday, May 22, at 14:00]
Presentation is scheduled to begin at 10:00
Convention Paper 6739 (Purchase now)
P15-6 A Computer-Aided Design Method for Dimensions of a Rectangular Enclosure to Avoid Degeneracy of Standing Waves—Zhi Liu, Fan Wu, Beijing Union University - Beijing, China
A method for designing dimensions of a rectangular enclosure to avoid degeneracy of standing waves and the corresponding computer-aided design software are presented in this paper. A math model to calculate many dimensions in favor of avoiding degeneracy of standing waves is created. The similarity of the normal frequencies regarded as degeneracy is limited under a specific condition. Based on the relationship between normal frequencies and the dimensions of a rectangular enclosure, the dimensions to avoid degeneracy can be chosen. A Computer Aided Design program is also developed to identify the dimensions that can be applied in the design of a loudspeaker cabinet or room to get the best acoustic effect.
[Associated Poster Presentation in Session P21, Monday, May 22, at 14:00]
Presentation is scheduled to begin at 10:20
Convention Paper 6740 (Purchase now)
P15-7 A 3-D Acoustic Simulation Program with Graphical Front-End for Scene Input—Achim Kuntz, Rudolf Rabenstein, University of Erlangen-Nuremberg - Erlangen, Germany
A program for full three-dimensional simulation of sound propagation in enclosures is presented that interfaces to a graphical interface for intuitive setup of complex simulation scenes. The simulation algorithm is based on the wave digital filtering principle, allowing for arbitrary reflection coefficients at object boundaries and walls for realistic results. Simulation scenes are defined in an object oriented way. As a graphical user interface to the simulation program, a modeler front-end for a ray-tracing program is used. Simulation setups can thus be built by graphically placing objects in the scene. Being open source, the proposed modeler can easily be customized if required. Simulation results are shown for several example setups demonstrating the possibilities of our approach.
Presentation is scheduled to begin at 10:40
Convention Paper 6741 (Purchase now)
P15-8 Absorptive Material Arrangement Method for Global Interior Noise Control in a Wide Frequency Range—Sung-Ho Cho, DM R&D Center, Digital Media Business - Suwon, Gyeong-gi, Korea; Yang-Hann Kim, Korean Advanced Institute of Science and Technology - Daejeon, Korea
A simple method is proposed to arrange absorptive material for global interior noise reduction in a wide frequency range. When an enclosure’s typical dimensions are of the order of several wavelengths or less, and sources and enclosure are geometrically complex, it is not easy to select the means that guide us to effectively control its noise by attaching absorptive materials on its walls. The proposed method, however, will lead the designer to better understand which treatments are most effective and how a better design can be achieved. The beauty of the proposed method is that one can easily find the absorptive material arrangement for global noise reduction unnecessary to calculate the sound field by using a perturbation method or boundary element method. This means that one can effectively find the absorbent’s arrangement because this method needs only eigen structures (eigen value and eigen function) of an enclosure.
Presentation is scheduled to begin at 11:00
Convention Paper 6742 (Purchase now)
P15-9 Real Time Acoustic Rendering of Complex Environments Including Diffraction and Curved Surfaces—Olivier Deille, Julien Maillard, Nicolas Noé, Centre Scientifique et Technique de Bâtiment - Saint Martin d'Hères, France; Kadi Bouatouch, Institut de Recherche en Informatique et Systèmes Aléatoires - Rennes Cedex, France; Jacques Martin, Centre Scientifique et Technique de Bâtiment - Saint Martin d'Hères, France
A solution to produce virtual sound environments based on the physical characteristics of a modeled complex volume is described. The goal is to reproduce, in real time, the sound field depending on the position of the listener and to allow some interactivity (change in material characteristics for instance). First an adaptive beam tracing algorithm is used to compute a geometrical solution between the sources and several positions inside that volume. This algorithm is not limited to polygonal faces and handles diffraction. Then, the precomputed paths, once ordered and selected, are auralized, and an adaptive artificial reverberation is used. New techniques to allow for fast and accurate rendering are detailed. The proposed approach provides accurate audio rendering on headphones or within advanced multi-user immersive environments.
[Associated Poster Presentation in Session P21, Monday, May 22, at 14:00]
Presentation is scheduled to begin at 11:20
Convention Paper 6743 (Purchase now)
P15-10 Comparisons between Binaural In-Situ Recordings and Auralizations—Konca Saher, Delft University of Technology - Delft, The Netherlands; Jens Holger Rindel, Technical University Denmark - Kgs. Lyngby, Denmark; Lau Nijs, Delft University of Technology - Delft, The Netherlands
The doctoral research of “Prediction and Assessment of Acoustical Quality in Living-rooms for People with Intellectual Disabilities” at Delft University of Technology investigates, among other issues, the applicability and verification of auralization as a quality assessment tool in acoustical-architectural design. This paper deals with the comparison between binaural in-situ recordings and auralizations obtained from computer simulations. Listening tests and questionnaires were prepared from auralizations to compare with the reference binaural recordings. The difficulties in evaluation of auralization quality are discussed. The results indicate that although auralizations and binaural recordings evoke different aural perception auralization is a strong tool to assess the acoustical environment before the space is built. Two commercial programs are used for the auralizations: ODEON and CATT-Acoustics.
[Associated Poster Presentation in Session P21, Monday, May 22, at 14:00]
Presentation is scheduled to begin at 11:40
Convention Paper 6744 (Purchase now)
