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"Physicists Achieve Perfect Acoustic Absorption"

Posted: September 15th, 2015, 5:34 pm
by MikeQuell
Source: http://motherboard.vice.com/read/physic ... =mbtwitter
Physicists at Hong Kong University of Science and Technology have experimentally demonstrated a system capable of perfect sound absorption. Acoustic waves go in, nothing comes back out. At all.

As often as we may like to imagine quietude, it's not a particularly natural phenomenon. An acoustic insulator may do a pretty good job of soaking up a small range of sounds, but some of that energy is always going to be reflected back, even if at very tiny scales. A material may be a highly complex composite of many different layers of many different viscosities, with each one tuned to absorb some wavelength of sound—what's called a gradient-index material—but imagining that material with all of the layers required to capture all of the different acoustic wavelengths is not very reasonable.

But there are other approaches.