Numerical techniques are used to study bone conduction hearing mechanisms. The military has an interest in bone conducted sound as personnel continue to experience hearing loss despite availability of full hearing protection. Particularly they need to identify better hearing protection over the entire audio range. A joint numerical/experimental program has been undertaken to quantify bone-conducted sound, identify paths along which sound propagates, and determine frequency-dependent characteristics of this conducted pressure. Specific cases in this work include coupling sound to the mastoid and measuring resultant pressures in the ear canal with and without earplugs. Canal pressure can be higher with ears blocked as plugs will trap conducted sound in a resonance mode, a phenomenon known as occlusion. In order to simulate this effect, digital images of a skull CT scan were used as the finite difference grid. Experimental results, based on behavioral and physiologic responses, were obtained from participants at UIUC to provide validation of the simulation. In both cases the occlusion effect is shown to be frequency dependent. The simulation software offers the possibility of evaluating the effect over a wide range of parameters such as earplug type, skull shape, and location of inputs. [Work supported by AFOSR FA9550-06-1-0128.]