Measurement the Noise Reduction of Doubly Curved Composite Sandwich Structures

Traditional single-layer panels are typically made of a thin metal or plastic and are often unsuitable for an interior finish because thin limp panels do not have enough resistance to combined acoustic-thermal loading. For medium and low frequencies, panels usually require a relatively large absorber thickness and weight. The sound absorber presented is a composite sandwich panel with an air gap between a comparatively stiff thick panel and a flexible thin plate. Under thermal loading, the flexible thin plate is buckled. When suitably adjusted to a particular curvature, an increase in stiffness is obtained which can increase the sound insulation by up to 27 dB between 250 Hz and 500 Hz.