writes "An idea for acoustic stealth technology proposed in 2008 was finallyput into practice. The abstract describes taking advantage of the"advantage of transformation acoustics and linear coordinate transformations that result in shells which are homogeneous, broadband, and compact. The required material parameters are highly anisotropic; however, we show that they are easily achievable in practice in metamaterials made of perforated plastic plates. " It is thought this technology might be useful for shielding ships from sonar or creating soundproof rooms.
One wonders if the Pop Sci editors missed something when they describe using "light waves" to accomplish this task."Link to Original Source