This research investigates the sound insulation properties — sound absorption coefficient and transmission loss — of a double porosity metamaterial and the functional dependence of such properties on the selection of underlying poroelastic material. The internal metamaterial geometry enables a global rotation phenomenon when the system is under a static compression. Using the finite element method, the influence of such compression upon the acoustic properties is quantified for its role in enhancing and tailoring sound insulation characteristics, while the additional influence of embedded rigid inclusions is examined. By applying these concepts to metamaterials composed from different poroelastic media, it is found that the acoustic properties can be tuned over strategic frequency ranges of relevance for sound insulation. In particular, the results demonstrate that for certain metamaterial compositions the absorption coefficient can be increased by about 100% and the transmission loss enhanced by 20% across a broad range of low frequencies by the introduction of the inclusions, while the compression constraint can increase the properties by 10 to 20% across narrow frequency bands. The outcomes suggest new possibilities for greatly enhancing the acoustic insulation properties of poroelastic materials in applications where space is limited and/or where added mass is not a concern.

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