Helmholtz resonator array for low-frequency sound absorption

An array of Helmholtz resonators is often used for reducing low-frequency noise because of the high performance at its resonance frequency. One of the very attractive characteristics of the resonator array is that its effective frequency band is much wider than what can be obtained by a single resonator. This paper discusses a method of designing a Helmholtz resonator array panel for low-frequency sound absorption. First, various experimental results are introduced and studied. Second, based on the experimental results, a theoretical method is presented that can predict reasonably well the panel’s absorption characteristics. Any configuration of resonator arrangement can be treated in the method, while all the resonators may or may not be identical. Comparisons between the predicted and experimental results reveal the accuracy of the proposed method. Finally, a numerical optimization is performed to design the Helmholtz resonator array panel. Some examples of optimal designs under some restrictions are also introduced.