Diffraction of Sound by an Array of Rectangular Reflective Panels

Abstract

An investigation in an anechoic room of the diffraction of sound by rectangular panels, similar to panels that have been used for acoustical purposes in concert halls and other auditoriums, confirms certain expectations based on well-known properties of both optical and acoustical diffraction: namely, (1) that, for wavelengths that are large as compared to the dimensions of the panels and the spacing between them, the incident sound on the panels is essentially all transmitted, and therefore for frequencies below a certain critical value, arrays of such panels are essentially nonreflective; (2) that, for wavelengths that are small, the panels reflect most of the sound incident upon them; and (3) that, for wavelengths that are of the same order of magnitude as the dimensions of the panels and spacings, there are complex diffraction effects.