Sea ice may be described as plates (on the order of 100 m wide, 3 m thick) interspersed with randomly spaced, randomly oriented, and randomly distributed in depth (on the order of 5 m) ridges. To determine the dominant factors affecting reflectivity from this medium, experiments have been designed using ultrasonic methods and plastic models that simulate particular features of sea ice. Initial tests were conducted with “infinitely” thick samples striated with parallel, equally and randomly spaced half-cylinders and compared with a theory due to Twersky; this theory appears to account for first order effects of sea ice on propagation loss. Results of the preliminary ultrasonic measurements will be presented and inferences discussed. Follow-on experiments, which will consider effects of preferred and ramdom ridge orientation and plate thickness, are expected to provide a baseline and a stimulus for refined theories of under-ice reflectivity and scattering.