Figure 2.

(a) The insonified portion of the cloak (|θ | < π/2) is patterned by sound absorbing Helmholtz resonators. The angular dependence of their resonances has been tuned via the resonator neck width w and depth t. (b–d) The theoretically and numerically computed absorption and impedance match is presented in dependence to the angle θ, i.e., the position of the individual Helmholtz resonators.