Tunable acoustic transmission control and dual-mode ventilated sound insulation by a coupled acoustic metasurface

In this paper, we present an alternative design for an acoustic metasurface with sparse units featuring open-ended pipes located on both sides of a central cavity, which can be tuned by designing the widths and length sizes. Band-stop and band-pass transmission control can be easily attained by alternating these units' periodic arrangements with and without intervals and can be theoretically computed by the transfer-matrix method. By combining four of these units, the formed coupled metasurface has a subwavelength of 0.127{λ} and can insulate broadband sound (4.2 cm for approximately 1000--1500 Hz). The working bandwidth is between the resonant frequencies of monopolar and dipolar modes, which correspond to a negative effective bulk modulus and a negative effective-mass density, respectively, whose mechanism is different from conventional ones. To help with the tuning, the acoustic-electrical analogy gives the operating frequency as a function of size parameters. Numerical simulations and experiments are used to verify the ventilated sound insulation and transmission control capabilities. This paper presents a structurally simple, lightweight, and multifunctional design with appropriate arrangements that can be applied to acoustic communications, architectural acoustics, noise control, and other related fields.