A microperforated panel (MPP) is usually used with an air-back cavity backed by a rigid wall to form a Helmholtz-type resonance absorber. In the case of a common perforated panel with larger perforations, a porous absorbent is usually located behind the panel to add acoustic resistance for efficient sound absorption. In the case of an MPP, if a porous layer is inserted in the cavity, the absorption may be deteriorated by the large acoustic resistance due to the porous absorbent. However, if the resistance is suitably adjusted, it is expected that a porous layer can widen the absorption frequency range by the additional damping by the porous absorbent. In this study, a single-leaf MPP absorber backed by a rigid-back wall with a porous absorbent layer in the cavity is analysed using an electro-acoustical equivalent circuit model and its absorption characteristics are discussed through the numerical examples.
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