Sound Transmission Loss of a Large-scale Meta-panel with Membrane and Platelet Attachments

To date, low frequency noise (< 500 Hz) remains an issue in automobile cabins. The phenomenon-known as booming noise-may cause discomfort to the passengers; making it undesirable. Conventional acoustical treatments are commonly applied to achieve cabin noise reduction. Conversely, effective low frequency noise control may lead to excessive acoustical treatment. This, in turn, affects the dynamic performance of the automobile. Recent studies have demonstrated the potential of membrane acoustic metamaterials as an alternative for low frequency noise control applications. However, these studies are generally limited to small-scale specimens. Accounting for practicality, it is imperative to extend earlier studies and consider large-scale specimens of similar construction. This paper demonstrates the preliminary experimental results for two configurations (different stacking orientation) of large-scale meta-panel with membrane and platelet attachments. Results indicated an improvement in sound transmission loss at specific frequencies below 500 Hz with the inclusion of a membrane-platelet layer. The results were, however, dependent on the stacking orientation of each layer forming the meta-panel. Subsequent work is in progress to validate the preliminary results and understand the dynamic behaviour of the meta-panel.