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.

Bazaars are among the few historical buildings that still continue to operate. The Bazaar in a city has been important not only from economic aspects but also from cultural and social aspects. Today, the empty space of such urban spaces, which can become a lasting space by creating a sense of belonging and peace, while meeting the needs of today's people, is felt very much. SOUND is one of the main factors in creating memories in the human mind. In order to investigate the role of SOUND in the traditional architecture of Iran, a research was conducted in the Vakil Bazzar of Shiraz. The final goal of this research is to investigate the quantitative and qualitative conditions of the SOUND using SOUND meter software in the Vakil Bazzar of Shiraz. The permissible level of noise pollution in urban spaces is 60 decibels based on the resolution of the Supreme Council of Environmental Protection of Iran for commercial areas. The results of this research indicate that in the quietest conditions, the noise pollution for at least 33% of the Bazzar space is higher than the maximum allowed amount of noise pollution. How to improve the SOUND conditions in Vakil Bazzar, such as reducing noise by creating a masking SOUND source, creating a pond and a fountain, is one of the most important results of this research.