The Coke can acoustic lens, surrounded by speakers, can focus sound waves to a space 1/25th the size of a wavelength. Image credit: Fabrice Lemoult (PhysOrg.com) -- When trying to focus sound waves ...

Sound system: photograph showing the array of loudspeakers on the far left. Also visible are the metamaterial lens of plastic spheres and the microphones used to acquire the images. (Courtesy: ...

Sound, like light, can be tricky to manipulate on small scales. Try to focus it to a point much smaller than one wavelength and the waves bend uncontrollably--a phenomenon known as the diffraction ...