Determining the Effect of Air Chambers on Rubber Insulation in Automotive Parts for Sound Absorption Coefficient and Transmission Loss

Abstract

In automotive industry, noise from the road, engine and environment are undesirable sounds which impacts the driver and passengers. In automobiles, the connection between the gear shifter mechanism and the transmission is carried out through cables and these cables go through a passage between the engine and the passenger compartment and rubber-based grommet parts are using for insulation. In this study, a phenomenon is investigated for shifter grommet parts. For using low sound transmission speed of air, air chambers are positioned perpendicular to the sound direction in insulation materials and tested with impedance tube of samples transmission loss and sound absorption coefficient. At these tests EPDM samples were used. On these samples, 2 types of air chambers with 4 mm and 6 mm diameter were considered having either 2 or 3 whole body or blind holes. Results showed that in the air chamber with 3 blind holes, test sample results are best up till 8% void in the insulation material. On the other hand, most of the test samples with holes showed better results than the one’s without the hole and the results showed that using low sound velocity of air can help to achieve better sound insulation properties in similar applications.