An article of footwear has an upper, an outsole attached to the upper, and a midsole. The outsole includes a ground-engaging surface and an inner surface disposed on opposite sides. The midsole has a footbed and a bottom surface disposed on opposite sides. The bottom surface opposes the inner surface to define a cavity therebetween. The article of footwear also includes a first series of projections extending into the cavity from one of the inner surface and the bottom surface in a first direction toward the other of the inner surface and the bottom surface. The article of footwear also includes a second series of projection extending into the cavity from one of the inner surface and the bottom surface in the first direction toward the other of the inner surface and the bottom surface. The article of footwear also includes a quantity of particulate matter disposed within the cavity.