Joint research by a Chinese-US team has been published in Applied Physics Letters, describing the experimental realisation of an acoustic field rotator. Field rotators are a specific type of "illusion cloak", which makes an object appear as something else; in this case, a rotated version of the same object. Whilst these devices have been made for electromagnetic waves, this is the first time it has been demonstrated for acoustics. The implementation relies on anisotropic metamaterials and provides another tool for controlling acoustic waves. Possible applications include medical ultrasound systems, where "the ability to rotate the sound waves could improve the contrast of ultrasound devices and allow them to image damaged tissue or diagnose diseases in ways they currently cannot. This is significant because ultrasound devices may be cheaper than other imaging modalities and do not use X-rays" (AsianScientist.com). However, the proof-of-concept device described is some way from clinical applications.