Membrane-type acoustic metamaterial using cork sheets and attached masses based on reused materials

To contain the environmental impact of modern buildings it is necessary to design in a sustainable way, making efficient use of energy resources and raw materials. The reduction of waste requires a review of the policy of valorizing raw materials by resorting to recycling and reuse as much as possible. In this study, a new membrane-type acoustic metamaterial was developed using a recycled cork membrane and fixing to this membrane masses obtained by reusing thumbtacks and buttons. About 42 samples were packaged by attaching different combinations of masses to the cork membrane. The specimens thus obtained were used to measure the sound absorption coefficient by means of an impedance tube. To improve the acoustic properties of the material, the benefits of membrane resonance absorption and cavity resonance absorption were coupled, leaving a 50 mm cavity at the end of the tube. Subsequently, the measurements were used to train a regression tree-based sound absorption coefficient prediction model. The results obtained suggest using these structures for the acoustic correction of the rooms.(c) 2021 Elsevier Ltd. All rights reserved.