Introduction: The aim of the present study was preparing polymeric materials and nanocomposites based on nanoparticles of zinc oxide in normal cases the coated with gelatin and comparing them in terms of sound transmission loss in different frequencies.  Method: This study was an experimental one. The materials used in the current study were included zinc oxide nanoparticles, polymer po...

Muffler is a part of the vehicle exhaust system that absorb or reflect sound waves to reduce exhaust noise. One of the most important determinants of a muffler performance is the amount of attenuation that has on its input wave; this parameter is known as sound transmission loss. Four - mic standard test is one way to determine this parameter which is used in this paper. In this study, a test d...

Introduction: Nowadays multiple techniques have been developed to noise control. One the most important way is the control based on sound absorption and insulation. The purpose of current study was to improve the acoustic properties of soft polyurethane foam regarding combined sound absorption and insulation characteristics. Materials and Methods: Polyacrylonitrile and polyvinylidine fluoride ...

Open cell aluminum foams have good acoustic dampening properties. In this research, in order to improve the sound damping capacity of these foams, 0.9, 1.5 and 3wt% carbon nanotubes were added to the aluminum foam. Foams were produced by the space holder method in powder metallurgy. The results showed that Al-0.9wt%CNT nanocomposite foam had the highest average sound transmission loss in the fr...