Acoustic shield blocks noise without blocking airflow

Advanced Materials

Technological Innovation Website Editorial Team - September 8, 2025

This prototype consists of five superunit cells, each containing three cells with a phase gradient. [Image: Zhiwei Yang et al. - 10.1038/s41598-025-04885-6]

Acoustic shield

Metamaterials , artificial materials whose behavior depends on their structure, not their chemical composition, have already entered the field of noise absorption and acoustic insulation .

But Zhiwei Yang and colleagues at Boston University in the US have shown that there are still many tricks up our sleeves in this field.

Yang created an acoustic shield that not only significantly blocks sound but also maintains airflow, making the technology viable in new environments such as factories, offices, and public spaces where diverse and unpredictable sound frequencies are common but airflow cannot be compromised.

The advancement focuses on so-called broadband muting. While this control over a wider range of sound frequencies has resulted in a slight tradeoff in maximum muting performance, it opens up new application and comfort possibilities.

The metamaterial can be left rectangular or rolled into multiple shapes, including cylinders, all while maintaining airflow. [Image: Zhiwei Yang/Xin Zhang]

Retains sounds, lets air pass through

The team calls its technology an ultra-open phase gradient metamaterial, and cites potential applications in fans, propellers, and air conditioning systems, aiming to reduce noise without obstructing airflow.

"[Our material] takes a smarter approach — more akin to noise-canceling headphones — effectively silencing a wide range of unwanted sounds," said Professor Xin Zhang, whose team had previously explored this architecture to address drone hum .

Compared to previous work, the metamaterial has gained a wide bandwidth. "It remains highly effective even when the noise changes in pitch or volume, making it much more practical in dynamic environments such as open-plan offices, ventilation systems, or transportation hubs, where sound sources are unpredictable and span a wide frequency range," Zhang said.

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