Helmholtz resonator with two resonance frequencies by coupling with a mechanical resonator

This contribution presents the acoustical properties and corresponding theoretical descriptions of a Helmholtz resonator with an integrated cantilever inside the Helmholtz resonator neck. The advantage of this resonator design is a second resonance frequency, which leads to a supplemental frequency region with high sound absorption properties. An analytical model is derived to calculate the resonance frequencies and the absorption coefficient of the resonator system. This model has been verified with finite element simulations for the resonance frequencies, taking into account several geometric parameter variations. It has been validated experimentally for the calculated absorption coefficients by impedance tube measurements. In conclusion, it has been found a high influence of the geometric parameters on the resonance frequencies and a broader sound absorption performance of the coupled resonator system