Sound absorption properties of microperforated panel with membrane cell and mass blocks composite structure

Microperforated panel (MPP) absorbers have been widely used in noise reduction and are regarded as a promising alternative to the traditional porous materials. However, the absorption bandwidth of a single-layer MPP is insufficient to compete with the porous materials. In order to improve the sound absorption ability of the single-layer MPP, membrane cell and mass blocks composite structure is introduced. Sound absorption properties of the MPP with membrane cell and mass blocks composite structure are studied by the impedance tube experiment. Results show that Membrane cell and mass blocks can change the sound absorption of MPP by introducing additional absorption peaks and valleys. To illustrate the role of membrane and mass in the sound absorption process, the acoustic properties of aluminum plate, aluminum plate with membrane, aluminum plate with membrane and mass are further investigated. When the membrane and mass are added, the sound resistance of the structure is increased and sound reactance of the structure jump abruptly near the sound absorption. This is mainly due to the local resonance of the membrane and mass. Therefore,combined with the characteristics of the sound absorption of MPP, the membrane and mass can further improve the sound absorption properties of the structure. Excellent performance of sound absorbing structure will be obtained by rational design of MPP, the size of membrane cell, the number, size and position mass blocks.