Subwavelength acoustic scatterers with extraordinary multipole scattering properties have attracted much research interest. We introduce an ultrasparse anisotropic acoustic scatterer array, which has degenerate monopole and dipole resonances, for total absorption of sound based on scattering cancellation of monopole and dipole moments. The dipolar scattering property of the scatterer is extremely anisotropic so that the dipole resonance can be switched off by rotating the scatterer about its own center by ${90}^{\circ }$. This feature leads to the scatterer-orientation dependence of mode degeneracy as well as the sound-absorption capability. Simulation and experimental results demonstrate the orientation-dependent sound-isolation property of the scatterer array. Moreover, the scatterer array is ultrasparse in that the spatial period exceeds the limit bounded by 4 times the absorption cross section of a subwavelength resonator ($d>4{\sigma }_{\mathrm{abs}}=2\lambda /\pi$). This ultrasparse and controllable sound-isolating material may have applications in many areas such as infrastructures, consumer electronics, and the automotive industry.

中文翻译：

---

使用简并各向异性散射体的超稀疏阵列实现非凡的声音隔离

具有非凡的多极散射特性的亚波长声散射体引起了很多研究兴趣。我们介绍了一种超稀疏各向异性声散射体阵列，该阵列具有简并的单极和偶极共振，可基于单极和偶极矩的散射抵消来完全吸收声音。散射体的偶极散射特性非常各向异性，因此可以通过以下方式使散射体绕自身中心旋转，从而关闭偶极子共振：${90}^{\circ }$。该特征导致模式简并性对散射体定向的依赖性以及吸声能力。仿真和实验结果证明了散射体阵列的取向相关的声音隔离特性。此外，散射体阵列非常稀疏，因为空间周期超过了以亚波长谐振器的吸收截面的4倍（$d>4{\sigma }_{\mathrm{腹肌}}=2\lambda /\pi$）。这种超稀疏且可控的隔音材料可能在许多领域中得到应用，例如基础设施，消费电子产品和汽车工业。