Effect of incidence angle and panel size on the phase of scattered energy from panel arrays

Abstract

This investigation focuses on factors that influence scattering from different ceiling panel arrays (e.g., incidence angle, and array size and density) by examining the scattered phase. A previous study by the third author [Torres and Vorländer, Acta Acust. (in press)] measured impulse responses using the maximum length sequence method at various receiver positions from scale model panel arrays of different sizes and densities. One interesting conclusion was that for multi-element arrays with panel dimensions and separation on the order of a wavelength, the reflected amplitude decreased, apparently due to destructive interference from inter-panel scattering. Analysis focused on the magnitude of the frequency response but the author noted that the phase curves could also contain information about scattered energy and the hypothesized inter-panel scattering. What the phase curves reveal is the subject of this study. It is expected that noticeable deviations from smoothness observed in the phase curves indicate non-specular scattering from the panels. The frequencies at which these deviations occur are examined to give insight into how the geometrical conditions of the panel array affect scattering.