Acoustic Analysis and Experimental Validation of Acoustic Metamaterial

In this study, a unique sound insulation performance of a lightweight acoustic metamaterial consisting of a stiff honeycomb plate coated with a thin rubber membrane was experimentally demonstrated. An acoustic transmission measurement of the acoustic metamaterial showed that the sound insulation performance of the acoustic metamaterial exceeded the mass law predicted performance in three frequency ranges. An analysis of the acoustic-structure interaction revealed that these unique sound insulation phenomena were due to the cancellation between two high-order eigenmodes of the periodic structure or a high-order eigenmode of the periodic structure and an eigenmode of the membrane in each honeycomb cell. Subsequently, a prototype of this acoustic metamaterial was applied to a vehicle and its effectiveness on vehicle interior noise was investigated. The results show that such materials can further improve the level of quietness with weight reduction in vehicles and other transportation applications.