Extraordinary sound tunneling through a barred horn via subwavelength hole resonance

Tuning the extraordinary acoustical transmission is shown to be practically feasible simply by controlling acoustical impedances induced by surface evanescent waves. We demonstrate this idea with an example of making a sound tunnel in an acoustical waveguide with a subwavelength short throat and a catenoid horn working below its cutoff frequency. The throat acting as a resonant aperture assists sound waves effectively tunneling through the normally barred horn, leading to resonant transmission of sound waves within an adjustable narrow band. The example may find its applications for highly efficient acoustical filters and transmitters. © 2011 American Institute of Physics.