Sound is one of the important factors in creating a good feeling in a mosque and it can play a role as a sensory medium to communicate spiritually with God. Therefore, the acoustic standards have defined the optimal level for the mosque in the field of various variables. In order to compare the acoustic conditions of the use of the mosque with the standard limits, the present research has carried out field measurements and software analysis of the standing position in order to simulate the prayer position. Form and volume are the two considered architectural parameters and Background Noise (BN), Reverberation Time (RT), and Sound Pressure Level (SPL) are the three acoustic variables of the study. A total number of 15 historical mosques in Tabriz are divided into three large, medium, and small volume categories and five form categories have been tested. The reference of the study is ISO3382-1 and ISO3382-2 and the measurements were made with B&K equipment. In addition to the direct achievements, the results have been adapted to international standards and show that the acoustic situation in the historical mosques of Tabriz, regardless of their volume and form, produces Sound in the range of 60 to 90 phones, and in terms of RT, have the suitable design from the volume point of view, but the lack of carpet flooring in some of them has increased the RT. The background noise in these examples is less than NC-25, which provides a quiet space for the user and provides the necessary concentration for individual worship.

In this article, an attempt has been made to estimate the amount of Sound transmission loss in a flat oval channel by applying the approach of statistical energy analysis. Correct estimation of Sound transmission loss in an air conditioning channel is of great importance due to the harmful effects of noise pollution in the environment on human health. Simulation with the statistical energy analysis method is a powerful approach to estimate Sound and vibration in problems in which we deal with complex and multi-part systems; is considered. In this method, first, a system is divided into several subsystems, and then by writing a matrix equation that includes the energy exchanges between subsystems and energy loss coefficients; It is investigated from the perspective of vibration and Sound estimation.On average, the model presented in this research is able to estimate the Sound transmission loss in different dimensions of the air conditioning channels according to the experimental results in the accuracy range of ± 2.5 dB. Considering that it seems that the results obtained from modeling with this method are in good agreement with the experimental data; The results of this research can be used as an efficient approach to estimate noise in oval shaped channels stretched in different lengths.

The first part of this paper discusses the importance of porous materials in passive noise reduction, types of porous materials, various applications of these materials, relevant acoustical and non-acoustical parameters, and different methods to measure them based on international standards were explained. In this part of the paper, definitions and experimental methods used in measuring the acoustic properties of the absorption coefficient and the Sound transmission loss based on international standards are presented. Then, while providing a comprehensive discussion of the Sound absorption mechanisms in porous materials, the types of Sound absorption mechanisms, including viscous, thermal, and structural losses, are described. The effect of different parameters on the variation of Sound absorption of porous materials has been presented. Also, various models, including experimental, laboratory, and analytical models used for expressing the acoustical and mechanical properties of porous materials, are discussed. Finally, a brief review is present for recent research areas on porous materials.

In this study, it is assumed that the outer shell of the sandwich has a core made of functional calibrated materials with piezoelectric patches and the inner shell is made of layered composites. Double-walled cylindrical shells have three external, internal and middle acoustic environments and are exposed to acoustic waves with a specific angle of effect. The dynamic equations of the structure are derived using the hypothesis of first-order shear displacement field of shells and Hamilton principle and together with the fluid / structure boundary conditions form the final equations. Using the Fourier series expansions of the input, return, and output Sound pressures and shell displacements, the dynamic equations are discretized to form a state matrix. After validating the results with existing articles, finally the effects, voltage applied by piezoelectric patches, percentage of functional materials, angle of fibers used in composites, types of composite materials, number of piezoelectric patches and angle of impact on the structure of Sound transmission behavior It has been evaluated in a certain frequency range. Finally, the voltage parameters applied by the piezoelectric patches, the percentage of functional materials, the angle of the fibers used in the composites, the types of composite materials, the number of piezoelectric patches and the angle of impact increased the Sound loss.