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IPFS News Link • Inventions

Acoustic Metamaterials Can Block 94% of Sounds

• https://www.nextbigfuture.com,

Boston University researchers Ghaffarivardavagh and Zhang wanted to block sound but not open air. They calculated the dimensions and specifications that the metamaterial would need to have in order to interfere with the transmitted sound waves, preventing sound—but not air—from being radiated through the open structure. The basic premise is that the metamaterial needs to be shaped in such a way that it sends incoming sounds back to where they came. They modeled the physical dimensions that would most effectively silence noises. Bringing those models to life, they used 3D printing to materialize an open, noise-canceling structure made of plastic. Trying it out in the lab, the researchers sealed the loudspeaker into one end of a PVC pipe. On the other end, the tailor-made acoustic metamaterial was fastened into the opening. Standing in the room, based on your sense of hearing alone, you'd never know that the loudspeaker was blasting an irritatingly high-pitched note. Inside the PVC pipe, you would see the loudspeaker's subwoofers moving. The team found that they could silence 94 percent of the noise which making the sounds emanating from the loudspeaker imperceptible to the human ear. Physical Review B- Ultra-open acoustic metamaterial silencer based on Fano-like interference


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