In May, the U.S. Naval Research Laboratory in Washington, D.C. revealed that by combining elastic responses with gradient materials, it is possible to create acoustic metamaterials. The research was published in Physics Today.
So, what exactly are acoustic metamaterials? They are advanced materials designed to trap sound within using special geometric structures. The question arises: can this new invention prevent airflow in the equipment’s chamber?
Combining elastic responses with gradient materials creates acoustic metamaterials.
In March 2019, a team of scientists from Boston University, including Professor Xin Zhang from the College of Engineering and PhD candidate Reza Ghaffarivardavagh from the Department of Mechanical Engineering, submitted a report demonstrating that acoustic metamaterials can effectively lock sound without obstructing airflow.
“Previously, we relied on thick, heavy walls for soundproofing. We believed there must be a more optimal method than pouring concrete; a material that could effectively lock in noise,” the research team stated.
This new method will be particularly useful in situations requiring soundproofing but where thick walls cannot be constructed, such as the exhaust vents of jet engines. Before the discovery of acoustic metamaterials, crew members had to wear earplugs to protect their hearing from extremely loud sounds. Now, they no longer have to endure that discomfort thanks to this new invention, which allows sound to be locked in while permitting airflow.
The research team utilized 3D printing to materialize an open structure made from plastic, which was then tested with a speaker. The experiment was successful, as the sound meter indicated that the speaker was still emitting extremely loud sounds, yet human ears could not hear any sound escaping.
After conducting several further experiments, the scientific team reported that the new invention has the ability to block 94% of noise, marking a significant contribution to various assembly industries, from aircraft and drones to construction.
