Broadband ventilated sound insulation in a highly sparse acoustic meta-insulator array

Ventilated acoustic insulators can block sound whereas simultaneously allowing airflow, which has potential applications for noise control in ventilation structures. In this paper, we propose a highly sparse acoustic meta -insulator array consisting of multiple tunable units. The meta-insulator unit with a minimum deep subwavelength thickness of 0.064 lambda has openings on two sides and a joint capacity. We propose an analytical model to reveal its physical mechanism. We numerically and experimentally demonstrate the highly sparse acoustic meta-insulator array with 20 units capable of ventilated sound insulation with a broad bandwidth of over 1 octave (from approximately 880 to 1915 Hz), a high sparsity of about 70%, and sound attenuation of more than 17 dB suitable for both near-field and far-field sound sources. Our designs may offer alternative solutions to ventilation noise control issues on various practical occasions.