Waveguide demultiplexer based on Helmholtz-resonator mediated extraordinary acoustic transmission

Abstract

The design of an acoustic demultiplexer based on in-line Helmholtz resonators is demonstrated analytically via a modified transfer matrix method and computationally through finite element simulations. The modeled system consists of a single input waveguide that splits in a Y-configuration into two output waveguides. Each output arm has a single tuned Helmholtz resonator embedded in-line along the length of the guide. The Helmholtz resonators in each arm consist of a single cavity with two necks—one directed towards the input and output sides of the guide. The phenomenon of extraordinary acoustic transmission results in near perfect transmission of sound along each output arm in a small frequency interval about the Helmholtz resonant frequency. The demultiplexed frequencies are determined by the physical dimensions of the Helmholtz resonator. Using a single Helmholtz resonator in each output arm means that the system is more compact compared to other proposed schemes using either side-loaded Helmholtz resonators or stubs.