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Sound absorption performance of cavity backed perforated panel on respect to the influence of flexible perforated membrane insertion was investigated by using a laboratory experiment. A layer of perforated flexible membrane was fitted inside the cavity backed MPP and the sound absorption coefficient was measured using transfer function based impedance tube technique. Since the inserted perforated membrane oscillated while the sound waves propagated through its perforations, it increased values of oscillating masses inside orifices which was then increased energy loss due to viscous damping associated to the span of amplitudes of the membrane resonance modes. The insertion gave possibility to get a cavity backed MPP design with the higher sound absorption coefficient in a wider low and mid frequency range compared to its of surface modification technique by means variation of the MPP porosity.

Perforated Flexible Membrane Insertion Influence on The Sound Absorption Performance of Cavity Backed Micro Perforated Panel