The Impedance of a Resistance Loaded Helmholtz Resonator

The impedance of a Helmholtz resonator damped by a thin porous layer in the form of a screen or cloth is calculated as a function of the distance between the aperture and the screen. It is shown that the input resistance of the resonator decreases very fast as the distance between the screen and aperture increases, whereas the aperture mass reactance passes through a maximum. The importance of these results with regard to design of resonators and perforated facings is discussed.