Bone conduction hearing systems use the body's natural ability to transfer sound through bone conduction. The sound processor picks up sound and converts it into vibrations that are transferred through the skull bone to the inner ear (cochlea). Thus, for patients with conductive or mixed hearing losses, patients with lasting hearing loss following a middle ear disease or malformations (such as microtia), the vibrations are bypassing the conductive problem in the ear canal or middle ear. Bone conduction devices currently on the market are divided into three types; transcutaneous direct drive, percutaneous (skin penetrating) direct drive and transcutaneous skin drive bone conduction devices. This evaluation focus on a sound processor used for a transcutaneous system.