A note on the effects of roughness on acoustic propagation past curved rough surfaces

Previous work on sound propagation past curved rough rigid surfaces demonstrated substantial changes in the insertion loss in the shadow zone due to the roughness ranging from +6 to -20 dB from their smooth counterparts. These previous data also lead to new propagation modeling efforts to incorporate the effects of roughness via an impedance model but the data and modeling efforts were limited to a narrow range of roughness and hill sizes. The current effort was designed to expand the range of roughness and hill sizes in order to explore the range of influence of the roughness. The work presented here confirms the effects of surface roughness as observed in previous work and indicates where the effects of roughness begin to emerge as well as where they transition between decreasing the insertion loss to increasing the insertion loss. (C) 2009 Acoustical Society of America