Assessment of non-exponential sound energy decays within multi-domed monuments by numerical and experimental methods

Sü Gül, Zühre
The key concern of this study is to investigate sound fields of single space superstructures sheltered with multiple-domes, in terms of their potential for featuring non-exponential sound energy decay characteristics. In this framework, Süleymaniye Mosque and Hagia Sophia Museum are selected as cases for investigating the effects of different material use and volumetric contribution on multi-slope decay formation. Methodology involves joint use of in-situ acoustical measurements and acoustical simulations. Relevant acoustical parameters including decay rates and decay times are computed by applying Bayesian decay parameter estimation. Analysis results of experimentally acquired and simulated data disclose double or triple decay formation in superstructures of Süleymaniye Mosque and Hagia Sophia Museum. To justify the phenomena and to understand the mechanism of energy exchanges, spatial sound energy distributions and energy flow vectors are studied by Diffusion Equation Model (DEM) simulations and intensity probe measurements over the case of Süleymaniye Mosque. Both computed and in-situ flow vectors highlight the contribution of sound reflective central dome versus absorptive carpeted floor on providing later energy feedback, creating a nondiffuse sound field. On the other hand, for Süleymaniye Mosque trial by DEM simulations the case of floor with marble instead of carpet has resulted in a much diffuse sound field, implying that the use of sound reflective floor material has prevented the multislope decay formation. Results over various acoustical data collection and data analysis techniques proved that energy fragmentation in support of non-exponential energy decay formation is due to both materials’ sound absorption characteristics and their distributions, as well as volumetric inter-space relations.


Assessment of Acoustical Indicators in Multi-domed Historic Structures by Non-exponential Energy Decay Analysis
GÜL, ZÜHRE SÜ; Çalışkan, Mehmet; Tavukçuoğlu, Ayşe; Xiang, Ning (2018-08-01)
The key concern of this study is to discuss the reliable acoustical metrics for analyzing particular sound fields within monumental multi-domed sacred spaces with an emphasis on multiple sound energy decay formation. The potential of such structures in featuring non-exponential sound energy decay characteristics necessitates new formulation of sound decay indicators in understanding of their sound fields. The early and late energy decay components within non-exponential sound energy decays can have a unique...
Predictions on absorption and scattering characteristics of acoustic scatterers modified with micro-perforated panels
Odabaş, Erinç; Çalışkan, Mehmet; Department of Mechanical Engineering (2012)
In this study, the basic absorption and scattering characteristics of acoustic scatterers, specifically Schroeder Diffusers, are investigated. Schroeder Diffusers are one of the most widely used acoustic scatterers in which the scattering phenomenon is predictable due to the geometry of the diffuser, based on a particular mathematical sequence. It is shown that it is possible to increase the amount of absorption by modifying the diffuser structure by means of adding perforated panels into the wells or narro...
Experimental characterization of a tuned vibration absorber
Aksoy, Tuğrul; Özgen, Gökhan Osman; Acar, Bülent; Gençoğlu, Caner (2016-01-01)
In this paper, experimental characterization studies conducted for a tuned vibration absorber is presented. The tuned vibration absorber has been particularly designed to reduce transverse resonant vibration response of a supported cylinder structure at its dominant two modes. Various testing configurations and techniques have been used such as transmissibility measurements, frequency response measurements, sweep sine testing, impact testing, and random testing. Different testing approaches were needed to e...
Optimization of the sound source position for shaping acoustically-structurally coupled cavities
Sorguç, Arzu; Shi, Qinzhong; Akagunduz, Haldun (null; 2001-12-01)
In this study, sound field inside acoustically-structurally coupled rectangular cavity excited by structural loading and sound sources is shaped by optimizing the position of the sound source. In the optimization, Most Probable Optimal Design (MPOD) based on Holographic Neural Network is employed and the results are compared with Sequential Quadratic Programming (SQP). It is shown that source position, rather than source strength, is more effective in acoustically controlled modes. The nodal positions for i...
Comparison of design codes for seismically isolated structures
Acar, Emre; Akyüz, Uğurhan; Department of Civil Engineering (2005)
This study presents information on the design procedure of seismic base isolation systems. Analysis of the seismic responses of isolated structures, which is oriented to give a clear understanding of the effect of base isolation on the nature of the structure; and discussion of various isolator types are involved in this work. Seismic isolation consists essentially of the installation of mechanisms, which decouple the structure, and its contents, from potentially damaging earthquake induced ground motions. ...
Citation Formats
Z. Sü Gül, “Assessment of non-exponential sound energy decays within multi-domed monuments by numerical and experimental methods,” Ph.D. - Doctoral Program, Middle East Technical University, 2015.