ON THE DESIGN OF RESONANT ABSORBERS USING A SLOTTED PLATE

Two numerical methods, i.e. a transfer matrix method and a finite elem ent method have been used to model the acoustic absorption of slotted plate type resonant absorbers where the damping is provided by a thin fabric covering the slits. Only the normal incidence condition was con sidered. Details are given on how to specify the necessary matrix elem ents and representative finite damping elements. Comparisons with an i mpedance tube measurement show that such numerical methods can predict the absorption characteristics with good accuracy.