Abstract: Traditional sound insulation designs typically employ enclosed structures, such as heavy partition walls and multi-layer sealed window frames. However, certain application scenarios require effective noise reduction while maintaining airflow, necessitating a departure from conventional design paradigms. Existing open acoustic insulation designs based on acoustic metasurfaces generally suffer from limited operational bandwidth—particularly in the mid-to-low-frequency range—often spanning less than half an octave. To address this limitation, this study proposes a large-scale ventilated sound barrier structure composed of coupled resonant metamaterial units. Simulation and experimental validation demonstrate that this structure achieves over 90% attenuation of incident sound energy within the 700–1700 Hz frequency band (covering more than one octave), with a thickness of only 50 mm (approximately one-tenth of the minimum wavelength in that band). This work provides critical experimental and theoretical evidence supporting the practical deployment of acoustic metamaterials in full-scale ventilated sound barriers.