Experiments performed with two coupled uranium metal cylinders are the first application to coupled systems of the /sup 252/Cf-source-driven neutron noise analysis method for obtaining the subcritical neutron multiplication factor. These coaxial cylinders were separated axially by various thicknesses of either air or borated plaster between the flat surfaces. In all measurements, the /sup 252/Cf neutron source was located at the center of the outer flat surface of one cylinder, and the two detectors were located in three configurations. By comparing the subcriticality from the measurements performed with borated plaster separating the uranium cylinders to those separated by air, it was found that the neutron multiplication factor was always increased by the insertion of borated plaster between the cylinders, regardless of their separation.