View metadata,Downloaded citation and from similar orbit.dtu.dk papers on:at core.ac.uk Dec 17, 2017 brought to you by CORE provided by Online Research Database In Technology Acoustics of ancient Greek and Roman theaters in use today Gade, Anders Christian; Angelakis, Konstantinos Published in: Acoustical Society of America. Journal Publication date: 2006 Document Version Publisher's PDF, also known as Version of record Link back to DTU Orbit Citation (APA): Gade, A. C., & Angelakis, K. (2006). Acoustics of ancient Greek and Roman theaters in use today. Acoustical Society of America. Journal, 120(5), 3148-3148. General rights Copyright and moral rights for the publications made accessible in the public portal are retained by the authors and/or other copyright owners and it is a condition of accessing publications that users recognise and abide by the legal requirements associated with these rights. • Users may download and print one copy of any publication from the public portal for the purpose of private study or research. • You may not further distribute the material or use it for any profit-making activity or commercial gain • You may freely distribute the URL identifying the publication in the public portal If you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim. THURSDAY MORNING, 30 NOVEMBER 2006 KAHUKU ROOM, 7:30 TO 11:50 A.M. Session 3aAAa Architectural Acoustics, Structural Acoustics and Vibration, Noise and Engineering Acoustics: Recent Developments in Acoustical Materials and Structures Brandon D. Tinianov, Cochair Quiet Solution, 1250 Elko Dr., Sunnyvale, CA 94089-2213 Kimihiro Sakagami, Cochair Kobe Univ., Environmental Acoustics Lab., Faculty of Engineering, Rokkodai, Nada, Kobe 657-8501, Japan Kirill V. Horoshenkov, Cochair Univ. of Bradford, School of Engineering Design and Technology, Bradford, BD7 1DP, U.K. Chair’s Introduction—7:30 Invited Papers 7:35 3aAAa1. Characterizing viscoelastic and anisotropic porous materials. Laurens Boeckx, Poonam Khurana, Gerrit Vermeir, Walter Lauriks ͑Laboratorium voor Akoestiek en Thermische Fysica, Celestijnenlaan 200D, BE-3001, Leuven, Belgium, [email protected]͒, and Wim Desmet ͑Katholieke Universiteit Leuven, BE-3001, Belgium͒ A wide range of commercial applications ͑building acoustics, food industry, automotive industry͒ can be found for porous materials. Accurate material characterization and modeling is vital for the use of these materials in multilayered systems due to increasing demands in acoustic comfort, noise legislation, and quality control during production. There is, however, a distressing lack in raw, accurate material data and measurement methods concerning the characterization of these materials. Measuring and modeling methods for the characterization of these materials will be presented. The experimental technique for the determination of the elastic properties is based upon the excitation of waveguides in porous materials. The other parameters of the Biot-Allard model are predicted using ultrasound. Acoustical properties can be predicted by using the measured structural material properties and incorporating them into a transfer-matrix-based multilayered model. 7:55 3a THU. AM 3aAAa2. Linking microstructure and acoustic properties of open-cell foams. Camille Perrot, Raymond Panneton ͑GAUS, Dept. of Mech. Eng., Universite de Sherbrooke, QC, Canada, J1K 2R1, [email protected]͒, and Xavier Olny ͑ENTPE DGCB URA CRNS, Audin 69518, Vaulx en Velin, France͒ A research program has been initiated in 2002 in order to link microstructure of high porosity open-cell foams to their acoustic properties. This paper is intended to highlight the main results of this study. The general objective of the research program is the determination of the acoustical macro-behavior from the physics at the local scale. A real rigid-framed porous media is studied. To this end, one needs first to determine the local geometry of the media, and second to solve over this geometry the partial differential equations that govern dissipation phenomena by thermal and viscous effects. The first step has been overcome by the technique of computed microtomography. This leads to experimental identification of the parameters of an idealized periodic unit-cell. The second step, solving harmonic heat and viscous fluid equations, is performed using Brownian motion and finite element simulations, respec- tively. Then, macroscopic behavior is obtained by spatial averaging of the local and frequency-dependent thermal and velocity fields. Results are presented in terms of two dynamic characteristic functions ͑viscous and thermal permeabilities͒ compared to impedance tube measurements. This computational methodology may be seen as a first step to optimize the microstructure of foams from a bottom-up approach for better sound proofing. 8:15 3aAAa3. Interlaboratory experiments on the characterization of the acoustical and related nonacoustical properties of porous media. Kirill Horoshenkov, Amir Khan ͑Univ. of Bradford, Bradford, UK͒, Frank Sgard, Francois Xavier, BecoLuc Jaouen, Amlie Renault, Nesrine Amirouche ͑Ecole Nationale des Travaux, Lyon, France͒, Jorn Hubelt ͑Gesellschaft fr Akustikforschung Dresden mbH ͑AFD͒, Germany͒, Francesco Pompoli, Nicola Prodi, Paolo Bonfiglio ͑Universita di Ferrara, Ferrara, Italy͒, Walter Lauriks, Laurens Boeckx ͑Katholieke Universiteit Leuven, Belgium͒, Giulio Pispola, Francesco Asdrubali ͑Univ. of Perugia, Perugia, Italy͒, Noureddine Atalla, Celse Amdin ͑Univ. of Sherbrooke, Sherbrooke, Canada͒, K. Mark Gmerek, and Adam Weston ͑The Boeing Co., Chicago, IL͒ A series of reproducibility experiments on the characterization of acoustical parameters of selected samples of porous media is carried out on a range of porous samples in several independent laboratories in Europe and North America. The data on the characteristic acoustic impedance and complex propagation constant are presented in this work. In addition, the assessment of the related geometrical parameters required for modeling the acoustic performance of porous media, namely the steady-state flow resistivity, porosity, tortuosity, viscous and thermal characteristic lengths, and thermal permeability, is carried out. Detailed procedures related to sample preparation, and installation are discussed together with data on the material property variation observed between individual material samples and laboratories. 3145 J. Acoust. Soc. Am., Vol. 120, No. 5, Pt. 2, November 2006 Fourth Joint Meeting: ASA and ASJ 3145 Downloaded 29 Jun 2010 to 192.38.67.112. Redistribution subject to ASA license or copyright; see http://asadl.org/journals/doc/ASALIB-home/info/terms.jsp 8:35 3aAAa4. Sound absorption characteristics of a honeycomb-backed microperforated panel „MPP… absorber. Kimihiro Sakagami, Kosuke Nakajima, Masayuki Morimoto ͑Environ. Acoust. Lab., Faculty of Eng., Kobe Univ., Rokkodai, Nada, Kobe, 657-8501, Japan͒, Motoki Yairi, and Atsuo Minemura ͑Kajima Corp., Chofu, Tokyo, 182-0036, Japan͒ Microperforated panels ͑MPPs͒ are typically made of a thin metal or plastic panel and are often unsuitable for an interior finish because thin limp panels do not have enough strength. In particular, an interior finish of room walls requires appropriate strength. In order to solve this problem, a honeycomb structure is attached behind MPPs to stiffen the construction. Thus, it is possible to stiffen an MPP without increasing its thickness, which is important to keep MPPs at their best absorption performance. Furthermore, a honeycomb can increase MPPs’ absorption coefficient in a similar way as a porous layer backed by a honeycomb. In this study, an experiment was performed to gain insight into the acoustical effect of a honeycomb structure behind MPPs and a simple theoretical model to interpret the experimental effects is presented. The experimental results show that the honeycomb affects the absorption characteristics of MPPs: the absorption peak increases and shifts to lower frequencies. This effect becomes more significant as the thickness of the honeycomb increases. The results from the theoretical model show the same tendency. This is attributed to the fact that the honeycomb makes a similar condition to local reaction in the back cavity. 8:55 3aAAa5. Development of new sound insulators with perforated board and honeycomb layer systems. Masahiro Toyoda and Daiji Takahashi ͑U. and E. Eng., Grad. School of Eng., Kyoto Univ., Katsura C1-4-392, Nishigyo-ku, Kyoto 615-8540, Japan, [email protected]͒ Two newly developed types of sound insulators are introduced in this study. The first type is derived from an analytical model of a vibrating surface with an impedance facing. The model is investigated theoretically; the results indicate the possibility of reducing radiation from the vibrating surface by giving appropriate impedance. To realize this effect, a model using a perforated board with a subdivided air cavity is proposed. It is shown theoretically and experimentally that this insulator can achieve radiation reduction at an arbitrary frequency. The second type is proposed from the viewpoint of the subdivision strategy. It presents the possibility of improving insulation by restricting the air-particle motion at the interface between the vibrating surface and air. This method for noise control has an attractive simplicity and considerable practical benefit. The attenuation mechanism is discussed theoretically