New 'acoustic metamaterial' cancels sound

Xin Zhang

Reza Ghaffarivardavagh

The metamaterial, ringing around the internal perimeter of the pipe's mouth, worked like a mute button incarnate until the moment when Ghaffarivardavagh reached down and pulled it free. The lab suddenly echoed with the screeching of the loudspeaker's tune.

By comparing sound levels with and without the metamaterial fastened in place, the team found that they could silence nearly all -- 94 percent to be exact -- of the noise, making the sounds emanating from the loudspeaker imperceptible to the human ear.

"We can design the outer shape as a cube or hexagon, anything really," he says. "When we want to create a wall, we will go to a hexagonal shape" that can fit together like an open-air honeycomb structure.

Zhang says the possibilities are endless, since the noise mitigation method can be customized to suit nearly any environment: "The idea is that we can now mathematically design an object that can block the sounds of anything," she says.