Прямокутні та циліндричні структури PGUOM працюють за одним і тим же принципом, забезпечуючи порівнянні характеристики широкосмугового глушіння/Zhiwei Yang and Xin Zhang
American researchers from the Zhang’s lab at Boston University has developed and presented a new metamaterial for broadband audio noise cancellation.
A team of researchers led by Master of Physics, Bachelor of Medicine and Mechanics, Master of Engineering, Professor Xin Zhang, created phase-gradient ultra-open metamaterial (PGUOM) for suppression broadband acoustic signals. As Professor Xin Zhang himself notes, PGUOM is more similar in principle to noise-canceling headphones.
“It maintains high efficiency even when the pitch or volume of the noise changes, which makes it much more practical in dynamic environments such as open offices, ventilation systems, or transportation hubs where sound sources are unpredictable and cover a wide range of frequencies. Early developments based on Fano resonance, created by our team, were like tuning a radio to lock in one station. PGUOM takes a more intelligent approach — it’s more like noise-canceling headphones, effectively suppressing a wide range of unwanted sounds”, — explains Xin Zhang.
According to the professor, the material consists of single or repeating supercells, each of which, in turn, consists of three elementary subwavelength cells. Solid barriers, are built into the first and third elementary cells, to create controlled phase shifts of incoming sound waves.The central cell remains open, providing unobstructed air flow.
These specially created phase shifts cause the full 2π-phase gradient in each supercell, transforming incoming sound waves into spurious surface waves — acoustic analogs of electromagnetic surface plasmons that are trapped and scattered along the surface. As a result, broadband noise is effectively suppressed, while airflow and geometric adaptability are maintained.
“Our design isn’t one-size-fits-all, and this is its advantage. It can be customized in terms of both frequency range and airflow intensity, depending on the application”, — says Xin Zhang.
Unlike traditional phase-gradient structures with uniform elementary cells, in the researchers’ design the central cell is enlarged to meet changing airflow needs without compromising on silencing performance.
“Chronic exposure to excessive noise, which is often overlooked compared to air and water pollution, can seriously affect human health, contributing to hearing loss, sleep disturbances, increased stress levels, and even cardiovascular disease”, — Xin Zhang emphasized.
Noise pollution also affects the lives of wildlife, changing their behavior patterns and destabilizing ecosystems. Thanks to recent advances in design aimed at creating lighter, more open, and broadband-enabled materials, the team is now tackling these challenges on a larger scale. The researchers have successfully moved from modeling to creating real prototypes.
“We are focused on integrating our developments into specific products and applications, while optimizing metamaterials for scalable manufacturing processes. We are also working to further improve the noise reduction efficiency by aiming for high attenuation levels over an even wider frequency range, while maintaining low airflow resistance and minimizing overall thickness”, — said Xin Zhang.
The results of the study are published in the journal Scientific Reports
Source: TechXplore
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