Ever wish you could crank your home theater system so the explosions in Michael Bay's movies rock you out of your chair but don't put you out of favor with the neighbors? How about providing your kid with a truly soundproof room while she grapples with a saxophone?
Fill your walls with ball bearings of a certain size and your wishes will come true. Well, it's not quite that easy, but that's the idea behind acoustic research out of Caltech. The researchers found that the right arrangement of ball-bearing-size particles lets sound move in one direction, but not the reverse.
In addition to keeping apartment dwellers and concertgoers happy, the one-way sound material could be used to sharpen medical ultrasound imaging. And because it can lower the frequency of a sound, it could be used to filter out high-frequency noises.
The material could also be used to harvest energy from sound waves by efficiently channeling the waves to devices that convert vibrations to electricity.… Read more