Sound absorption and transmission by periodically supported double panel structures

Abstract

Double panel structures are frequently used in modern lightweight constructions, e.g., as factory roofing. Measurements indicate that these structures may provide the majority of low‐frequency absorption in the spaces they enclose. Conventional infinite double panel models significantly underestimate the absorption provided by these structures. As a result the authors have instead modeled these surfaces as two parallel infinite arrays of simply supported rectangular panels separated by a finite depth airspace, thus introducing component panel dimension as a model parameter. When the incident wave field is plane, the panel motions and the reflected, interpanel and transmitted acoustic fields may be expanded in functions periodic in the panel dimensions and their component strengths determined by application of sets of boundary conditions. The fraction of the incident energy that is either dissipated by each panel layer or transmitted may then be calculated. Absorption coefficients calculated in this way are consistent with those measured for factory roof structures and indicate that panel damping may control low‐frequency sound absorption.