Reverberation time control by acoustic metamaterials in a small room: Fid-Bau Portal

Reverberation time control by acoustic metamaterials in a small room

Qu, Sichao / Yang, Min / Xu, Yunfei / Xiao, Songwen / Fang, Nicholas X.

Abstract In recent years, metamaterials have gained considerable attention as a promising material technology due to their unique properties and customizable design, distinguishing them from traditional materials. This article delves into the value of acoustic metamaterials in room acoustics, particularly in small room acoustics that poses specific challenges due to their significant cavity resonant nature. Small rooms usually exhibit an inhomogeneous frequency response spectrum, requiring higher wall absorption with specific spectrum to achieve a uniform acoustic environment, i.e., a constant reverberation time over a wide audible frequency band. To tackle this issue, we developed a design that simultaneously incorporates numerous subwavelength acoustic resonators at different frequencies to achieve customized broadband absorption for the walls of a specific example room. The on-site experimental measurements agree well with the numerical predictions, attesting to the robustness of the design and method. The proposed method of reverse-engineering metamaterials by targeting specific acoustic requirements has broad applicability and unique advantages in small confined spaces with high acoustic requirements, such as recording studios, listening rooms, and car cabins.

Highlights • Achieving uniform acoustic environment by acoustic metamaterials with unique properties and customizable design. • Combining FEM simulation method with ray-acoustics-based theoretical model to predict the reverberation time in a broad frequency range. • Optimal metamaterial absorption given by reverse-engineered model and achieved by recent customization technology. • Metamaterial-based solution outperforms the traditional foam-based approach by a significant margin, verified by the test in a real room.