Metamaterials Could Reduce Marine Noise Pollution

Metamaterials to tackle noise pollution in marine ecosystems are currently under development within the POSEIDON project - Unconventional principles of underwater wave control in the sub-wavelength regime – funded by the European Research Council through a Starting Grant.

At the core of the study is the development of mechanical metamaterials – composite materials that exhibit unconventional quasi-static and dynamic properties – capable of controlling deformation and the propagation of waves (both elastic and/or acoustic). The aim is to enhance current technologies for the reduction of underwater noise pollution, a phenomenon that continues to grow due to the increasing intensity of human activities in marine ecosystems, such as the installation of offshore wind farms, wave energy harvesting, and subsea mineral extraction.

Current solutions are generally ineffective, particularly at low frequencies. The main challenge lies in the way sound propagates underwater, where wavelengths are five times longer than those in air, and the fluid’s density (1,000 kg/m³) is comparable to that of the solid materials typically used to construct barriers. These factors necessitate the use of very thick barriers, which can be environmentally invasive.

This is where metamaterials and their unconventional properties come into play. Unlike traditional materials, the quasi-static and dynamic responses