Scattering properties of labyrinthine metamaterials with different numbers of resonance units

This paper describes a series of labyrinthine acoustic metamaterials with different numbers of resonance units. The research is carried out based on numerical modeling of impedance tubes. We find that the realization of slit sound transmission using resonant dimers is related to the coupling interaction between the samples and the distribution spacing, and that each order of metamaterials can realize full slit sound transmission only at the corresponding distribution spacing. For labyrinth-type acoustic metamaterials with higher refractive indices, the phenomenon of acoustic capture is more pronounced for samples capable of acoustic capture at the monopolar resonance frequency. The acoustic isolation under sparse spacing distribution can be improved by increasing the pressure difference between the sample center and the background medium. This work can be useful for the design of labyrinth-type acoustic metamaterials in terms of sound insulation, acoustic capture, and acoustic lensing.