HYBRID ACTIVE AND PASSIVE MICRO-PERFORATED PANEL ABSORBER FOR SUPPRESSING IRREGULAR ENCLOSED SOUND FIELD

This paper investigates the sound absorption performance of hybrid active and passive micro-perforated panel absorber (MPPA) for suppressing the irregular enclosed sound field. The hybrid MPPA is strongly coupled with the irregular enclosed sound field so that it serves as a sound energy dissipating component. The sound absorption is highly dependent on its layout on the boundary of the enclosed space, which needs to be explored in detail. The fully coupled enclosure-hybrid MPPA model is established using modal analysis approach. The passive and active sound absorption performance of the hybrid MPPA in various layout situations are explored. Results show that the energy dissipation of full MPPA coverage is better than the partial coverage case owing to the weakened coupling effects or the wave mismatch between the enclosure and the MPPA cavity. Applying active control to suppress the sound field of the MPPA cavity can generate pressure difference across the MPP, which further dissipates energy of the undamped resonances of the coupled system to a minimum. The active control performance will decrease for the partial covered MPPA owing to the complicated couplings between the enclosure and the MPPA cavity.