Basic Study on Sound Absorbing Mechanism of MPP Affected by Bending Resonance

Abstract

Micro-perforated panels with honeycomb core joined or contacted behind are molded by 3D printer, and their sound absorption coefficients are measured by an acoustic impedance tube. When the thickness of panel becomes as thin as 0.1mm, its bending natural frequencies concentrate and couple with Helmholtz resonance. Based on the interpretation of such thin MPP’s sound absorbing mechanism, a new type of MPP with cylinder around each hole is proposed so as to effectively control the natural frequency of panel bending and Helmholtz resonance separately. It is evaluated for such type of MPP to improve the performance of lower frequency range.