Bone conduction sound, the transmission of sound as vibrations in the skull bone, is used in several areas, forexample for hearing aids, in audiometry, and in communication systems. The bone-anchored hearing aid (BAHA)has been commercially available for many years. This device utilizes titanium screws attached to the skull bonepenetrating the soft tissues thus providing a rigid attachment to the skull bone. Subjects equipped with suchtitanium screws have proven important for investigation of bone conducted sound and in the present paper anoverview of some results from different studies on such patients is given. Included are results from investigationsof resonance frequencies, propagation delays, and transcranial (cross-skull) attenuation.