Ultra-broadband ventilation sound insulation by honeycomb hollow-out acoustic metasurface

Conventional ventilation sound insulation requires closed cavities to sustain strong acoustic resonance for reflecting incident waves. In this Letter, we propose a different meta-structure design that uses honeycomb hollow-out acoustic metasurface (HHAM) to realize ventilation sound insulation. The HHAM unit exhibits dual capabilities of very high ventilation sound insulation at resonance and also effective broadband sound attenuation. The well-designed multi-unit HHAM design achieves fine performance with an ultra-thin profile of only 53 mm (0.17λ) and 30% open area with average sound transmission loss exceeding 15 dB from 1100 to 2500 Hz. The proposed design offers a compelling combination of ultra-broadband, effective ventilation, structural simplicity, and fabrication feasibility. Experimental results agree well with numerical simulations and theoretical predictions. Our findings offer a promising pathway for the design of ventilated acoustic metasurfaces and may facilitate practical applications in noise control and architectural acoustics.