Optimal design method of Helmholtz resonators for noise control in enclosures

The analytical formulas of optimal damping ratio and working frequency band of a Helmholtz resonator for the interior noise control were developed and experimentally validated.Based on the coupled acoustic equations between the enclosure under control and a Helmholtz resonator,formulas for calculating optimal damping ratio and working frequency band of the resonator,to minimize the targeted sound pressure level inside the enclosure,were obtained.Then,detailed steps using the optimally designed acoustic resonators to attenuate noise in an enclosure were also proposed.Finally,a series of acoustic measurements were conducted in a one-dimensional duct to validate the developed formulas.The theoretical and experimental results demonstrated that the presented optimal design method can predict the optimal damping ratio and working frequency band for Helmholtz resonators with high accuracy,and it has a great potential in the interior noise control from low to middle frequencies.