Sound Isolation and Giant Linear Nonreciprocity in a Compact Acoustic Circulator

Acoustically Isolated The control of sound transmission is desirable in a number of circumstances from noise suppression to imaging technologies. Fleury et al. (p. 516 ; see the cover; see the Perspective by Cummer ) studied a subwavelength acoustic meta-atom consisting of a resonant ring cavity biased by an internally circulating fluid. The direction of rotational flow of the fluid (air) changed the resonant properties of the ring cavity, allowing the propagation of sound waves within the cavity to be controlled. With several ports connected to the cavity, sound could be directed to a certain port while isolating transmission in another.