Design and verifications of three building acoustic metamaterials for simultaneous noise insulation and ventilation

Ventilated acoustic metamaterials with simultaneous high noise insulation performance and sufficient ventilation aera are eagerly needed nowadays. Many acoustic metamaterials with high insulation capabilities are achieved at the expense of ventilation area of proposed configurations. Thus, there is a tradeoff between noise insulation capability and ventilation efficiency in metamaterial designing. Besides, most of the ventilated acoustic metamaterials are generally tested in impedance tubes, and they are seldom verified via building acoustic sound insulation laboratory testing. In this study, the traffic noise characteristics of two typical residential building away and nearby the main traffic road are measured, which both reveal that the traffic noises cover a broad frequency range of 200 Hz∼4000 Hz. Then, three ventilated acoustic metamaterials with the same out diameter (152.4 mm) but different ventilation areas (interior diameters of 29 mm, 60 mm, 100 mm) are investigated in detail via numerical simulations and experiments. The three metamaterials are fabricated with additive manufacturing techniques and their transmission loss performances are tested in impedance tubes firstly. Finally, their noise insulation performances are verified in the building acoustic sound insulation laboratory, where the acoustic excitation is white noise generated by a diffuse sound source and the sound transmitted into the receiving room is investigated. This study will pave a solid foundation for the applications of ventilated acoustic metamaterials.