Biomimetic acoustic metamaterial design for architectural applications

Abstract

This study investigates the potentials of acoustic metamaterial (AMM) applications in room and building acoustics by means of impedance tube experiments. With their extreme properties in either sound absorption or transmission loss, AMMs can perform better than many traditional acoustic materials in buildings. Importantly, they are also more sustainable and hygienic than fibrous and porous materials. Depending on the matrix material used, AMMs can vary in transparency and color. Considering both their acoustic and aesthetic values, this study develops different types of metamaterial for possible uses as a partition wall, a surface layer, or a design element. The proposed metamaterials are primarily based on the exploration of ratios and forms from nature – the golden ratio, web-labyrinthine structures, genetic and neural systems such as DNA molecules and the synapse structures in the brain – reproduced on a sub-wavelength scale. These abstractions are then combined with the 3D space coiling and 3D labyrinth approaches of AMM design. Modules of the proposed AMMs are manufactured in a 3D printer and tested in an impedance tube to estimate their normal incidence sound absorption coefficients and transmission loss characteristics. Based on the results obtained, the modules with the higher performances are used in the design of partition walls of varying heights. Two real-case architecture studios are simulated with and without the proposed AMM interventions over field test-tuned acoustical models of the studios to assess the effectiveness of such an approach in a possible acoustical design problem.