A groundbreaking advancement in acoustic metamaterials has emerged from the Zhang Lab at Boston University, signaling a transformative leap in sound control technology. This team, under the leadership of Professor Xin Zhang, has published a pioneering study introducing what they term “Phase Gradient Ultra-Open Metamaterials” (PGUOM), a novel design enabling broadband acoustic silencing without compromising airflow. Their latest research, published in the prestigious journal Scientific Reports, offers a compelling solution to the longstanding challenge of managing complex, dynamic noise environments in practical settings.
The quest to simultaneously suppress unwanted noise and maintain air circulation has fueled extensive research for years. Traditionally, acoustic silencers achieve narrowband sound attenuation by relying on resonant mechanisms tuned to specific frequencies. However, these conventional designs falter in real-world scenarios where noise spans a broad spectrum of frequencies and fluctuates unpredictably. The innovation brought forth by the Zhang Lab breaks this paradigm by leveraging advanced phase-gradient metamaterials, a class of artificially engineered structures designed to manipulate acoustic waves with extraordinary precision.
At the heart of their approach is the creation of ultra-open metamaterial architectures—structures featuring intricately designed rectangular and cylindrical elements that permit substantial airflow while still delivering high-performance noise cancellation. This balance is critical for applications ranging from HVAC systems and industrial ventilation to transportation hubs and open-plan offices, where persistent airflow is essential but noise levels must be carefully managed. The PGUOM designs draw upon complex computational simulations to fine-tune the metamaterial phase gradients, enabling broadband sound silencing that adapts dynamically to changing acoustic environments.
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One of the key breakthroughs in their work is overcoming the typical trade-off between peak silencing efficiency and bandwidth. Conventional designs achieve high noise attenuation only within narrow frequency bands, but the PGUOM achieves a broad spectrum of silencing, akin to noise-canceling headphones that adjust to a range of sounds in real-time. This is enabled by their use of phase gradient control—precisely shifting the phase of incoming sound waves—to cause destructive interference across a wide frequency band. Consequently, this metamaterial provides robust noise suppression even as sound pitch and amplitude vary, a feature that dramatically broadens its practical utility.
From a structural perspective, the PGUOM’s ultra-open configuration is more than a design choice; it is a functional necessity. Unlike conventional dense materials, which impede airflow and degrade system efficiency, these open metamaterials maintain ventilation while achieving impressive acoustic performance. Importantly, samples of these metamaterials were fabricated using advanced commercial 3D printing techniques, demonstrating their feasibility for scalable manufacturing and potential integration in diverse engineering systems.
This research builds on the Zhang Lab’s legacy in acoustic metamaterial silencers, an area where they have consistently pushed the boundaries of physics and engineering. Their early work, dating back to 2019, focused on sound shields that harnessed Fano resonance effects to block narrowband noise sources while preserving airflow. These initial findings proved critical in environments such as fan and propeller systems, where targeted noise reduction was needed without obstructing ventilation channels.
Extending beyond these foundations, the team’s current work embraces multi-band, broadband, and tunable acoustic silencing strategies, making the technology highly adaptable to multifaceted noise challenges. The intelligent design of the PGUOM reflects a nuanced understanding of acoustic wave propagation and reveals how artificial material structuring can augment or suppress sound in unprecedented ways. Their computational models simulate realistic conditions, mapping how sound waves interact with the metamaterial at different frequencies and angles, ensuring reliable performance in chaotic soundscapes.
Professor Xin Zhang emphasizes that the PGUOM represents a “smarter approach” to noise control—akin to having active noise-canceling headphones built into the environment itself. This capability is especially valuable in dynamic and open spaces where sound sources are numerous and varied, rendering traditional silencers ineffective. The metamaterial’s broadband capability ensures continuous sound suppression despite fluctuating noise characteristics, offering a new paradigm for sound management in public and industrial settings.
Beyond the technical merits, the project also carries significant societal implications. Noisy industrial environments, crowded offices, and bustling transportation centers all contribute to noise pollution, which is linked to a range of health and productivity issues. Innovations like the PGUOM open pathways to quieter, healthier spaces while maintaining essential ventilation, thereby supporting both environmental comfort and operational efficiency.
From a commercialization standpoint, the research team has already moved to secure intellectual property rights surrounding their invention. A U.S. provisional patent application was filed, followed by an international PCT application, underscoring the novelty and potential market impact of their phased array ultra-open metamaterial technology. These legal protections pave the way for collaboration with industry partners interested in integrating these metamaterials into next-generation acoustic management solutions.
Looking forward, ongoing efforts will likely focus on refining the metamaterial structures for specific industrial applications, scaling up fabrication techniques, and conducting real-world trials to validate performance under operational stresses. The intersection of computational modeling, additive manufacturing, and experimental validation in this research exemplifies how interdisciplinary collaboration drives innovative technology development.
In summary, the PGUOM developed by the Zhang Lab represents a landmark achievement in acoustic metamaterial research, combining theoretical rigor with practical applicability. By innovating phase-gradient control in ultra-open structures, the team has unlocked a versatile, broadband approach to acoustic silencing that maintains airflow—a balance previously elusive to engineers and scientists alike. As this technology matures, it promises to redefine standards for noise control across multiple sectors, enhancing human environments with elegant scientific solutions.
Subject of Research: Not applicable
Article Title: Phase gradient ultra open metamaterials for broadband acoustic silencing
News Publication Date: 1-Jul-2025
Web References:
https://www.nature.com/articles/s41598-025-04885-6
References:
DOI: 10.1038/s41598-025-04885-6
Image Credits:
Photo courtesy of Zhiwei Yang and Xin Zhang.
Keywords
Acoustics, Physical sciences, Material properties, Engineering
Tags: acoustic metamaterialsadvanced phase-gradient metamaterialsairflow and sound suppressionBoston University researchbroadband acoustic silencingdynamic noise environmentshigh-performance noise cancellationinnovative sound shield designnoise control technologyPhase Gradient Ultra-Open Metamaterialsreal-world noise management solutionsXin Zhang acoustic innovations
