Sound characteristic analysis of Multi-layer sound- absorbing materials using impedance tube

Abstract

With the development of the field of transportation, vehicles have come to be driven fast. As a result, due to their high speed, railways are the cause of increased noise inside the railway vehicle. Methods for reducing noise present themselves in various ways. However, it is difficult for a method to be effective without a costly and difficult implementation of technology. In general, to improve the characteristics of vehicle interior noise conditions, which can increases the effect of sound absorbing or insulation materials, it is necessary that any sound absorbing material be located between the outer and inner walls of the vehicle. In this paper, we perform an experiment on the acoustic characteristics of a composite multilayer type sound-absorbing material that can be used to reduce the interior noise of a vehicle. In our tests, we used an impedance tube, which can scan a plane wave with a speaker for the test-material. The tube is fabricated in a circular symmetrical shape. This overall method can be used to evaluate acoustic transmission loss. The results found in this study can be used to show that the selection of a multi-layer sound-absorbing material can allow users to achieve the characteristics of noise reduction. With the results delineated in this study, a multi-layer high density material can be confirmed to show improved performance this material can also be used to check the characteristics of the frequency response of the shape of the surfaces.