In general, factory roofs consist of two parallel layers of sheeting: the surface facing the interior comprises flat rectangular panels, and the outer surface corrugated ones. In tests of such constructions, absorption coefficients of 0.5 or higher have been observed in certain 1/3-octave bands below 1 kHz. Simple theories which model the roof as two parallel, uniform plates of infinite extent do not account for these observations. We have recently developed a new theoretical model which models the roof as two infinite parallel arrays of periodically supported rectangular plates. This theory, described below, has suggested how large values of absorption may occur. Supporting experimental measurements are also described briefly.
periodic structures, double panels, sound absorption, roofs
Acoustics and Noise Control
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