Acoustic velocity and strain data were obtained on two GT-2 samples as part of a study using acoustic data to infer or characterize volume-averaged rock microstructures. The pressure dependence of these data were compared to the pressure dependence of permeability, measured on adjacent samples, in a preliminary effort to study the relation between the microstructure networks controlling these two bulk physical properties. For pressures below about 1 kbar, the permeability data agree well with a function involving the cubic power of the compressional velocity modulus. This relation is suggested from comparison of the Kozeny relation for permeability to the form of the functional dependence of elastic moduli on porosity and pore strains. Correlation suggests that in such rocks, crack strains are essentially linear with pressure and that the same network of cracks controls both permeability and elastic properties