The primary goal of this study was to characterize the influence of the pore-saturated gas media and their physical properties on the elasticity of porous ceramic materials. Resonant ultrasound spectroscopic measurements were performed on test specimens of alumina with similar to 40% porosity, zirconia with similar to 48% porosity, and sintered fully dense zirconia to determine the hydrostatic pressure-dependent macroscopic elasticity. Here, we report the variation of elasticity of porous and full dense samples over approximately five orders of magnitude (800-0.02 psi) in absolute pressure. The time evolution of mechanical equilibrium of the porous materials at low pressure and high-temperature conditions will also be discussed.