Sound transmission loss of a large-scale meta-panel with membrane acoustic metamaterial

In automobiles, booming noise exists typically at low frequencies (< 500 Hz) within the passenger cabin as a result of vibroacoustic coupling. This may cause passenger discomfort and is certainly undesirable. Generally, traditional acoustical treatments are applied in the cabin for passive noise control. However, excessive treatments may be required for effective low frequency noise control. As such, the overall weight of the automobile is increased; affecting its mobility performance. It is, therefore, imperative to explore other options for such purpose. Recently, researchers have demonstrated the potential of membrane acoustic metamaterials in attenuating low frequency noise based on small-scale specimens. For practicality in the industry, it is necessary to consider larger specimens. This paper presents the preliminary experimental findings for two configurations of a large-scale meta-panel with membrane acoustic metamaterial. It is shown that sound transmission loss may be improved at specific frequency range with the inclusion of a membrane layer. Moreover, the acoustical performance is also affected by the stacking orientation of the meta-panel. Further work to understand the dynamic behaviour of the meta-panel and validate the experimental results is in progress.