In the oil industry there is a need for obtaining physical properties of potential reservoir rock from in-situ measurements. Acoustic measurements can be executed as borehole refraction measurements in the petrophysical case and as crosswellshooting in borehole seismics. A quantitative determination of permeability from acoustic measurements cannot be made because a suitable model is not yet available. It is suggested that, by including the permeability as an energy loss term in the mathematical model, this determination might become possible.