Absorption characteristics analysis of membrane sound absorber with magnet

This paper presents a membrane sound absorber (MSA) with tunable properties for low-frequency sound absorption. A simple method to predict the resonance frequency is proposed; the resonate frequencies predicted show good agreements with the experimental ones. The analysis indicate that the iron-platelet-magnet resonance mechanism introduced by the tuned magnetic field is the main factor leads to the appearance and shift of absorption peaks in low-frequency region, which are almost independent of the back cavity. This demonstrates that the structure has strong potential to achieve an extremely thin and low-frequency tunable-sound-absorption design which can be easily adapted to the noise source variation.