Ashok chakra-structured meta-structure as a perfect sound absorber for broadband low-frequency sound

We present thin acoustic meta-structures with subwavelength dimensions through which almost perfect sound absorption is achieved in the low-frequency domain. Our overall strategy builds on the fact that the sound absorption capabilities of the meta-structures primarily depend on the geometric dimensions and can easily be reconfigured as per requirements through a change of geometry. To analyze various possibilities, we optimize the geometric structure through hybrid regression analysis using the genetic algorithm approach and finite element-based numerical simulations so that the geometry is tuned for high attenuation of acoustic signals over a broad range of frequencies. Both theoretical and experimental data show good parity and are able to establish the meta-structure nature of the assembly with respect to different frequency bands in the low frequency domain.