Noise pollution has posed persistent challenges to the sustainable development of urban and built environments. Prior efforts have been mainly devoted to enhancing the performance of sound insulation, with comparatively less attention paid to fostering pleasant soundscapes. Here, we propose a multi-functional meta-barrier engineered for broadband sound reduction with ecological integration, while also enabling modulation of environmental conditions. By recycling the rainwater, the volumes of the acoustic cavities can be adjusted to block over 90% of sound energy in the range from 300 to 1600 Hz, following an optimization mechanism based on hybrid resonances. Meanwhile, the hydroponic plants can be set up in the cavities and further absorb more acoustic energy as porous materials. Besides the mitigation of unwanted sound, this environmentally friendly design also exhibits the characteristics of ventilation and thermal insulation, thereby creating a restorative urban space. The verification consisting of simulations and experiments is conducted to demonstrate the validity of a full-size sample across diverse conditions. By merging sound insulation with other ecological benefits, our design provides a versatile solution for noise challenges with potential applications in urban environmental infrastructure. • Double-layer acoustic ventilated barrier with nested Helmholtz resonators (10 cm, λ/3.6, sub-wavelength). • Broadband sound reduction in 300-1600 Hz: 20.1 dB average; ∼136% fractional bandwidth. • Greenery enhances physical sound insulation and perceived acoustic comfort. • Ventilated design enables airflow and thermal insulation (∼4.8 °C drop). • Rain-chain harvesting enables hydroponic cultivation in barrier; feasibility verified.
Xu et al. (Fri,) studied this question.