»Assessment of Non-Exponential Sound Energy Decays within Multi-Domed Monuments by Numerical and Experimental Methods

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 multi-slope 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.