Active middle ear implants are classified as piezoelectric implants,
which use the properties of piezoelectric materials.
There are two types of piezoelectric implants: monomorphic
and dimorphic; electromagnetic transduction uses a magnet,
usually a rare earth magnet (e.g. samarium cobalt) and an
energizing coil. This magnetic field causes the magnet to vibrate,
which in turn, through the tympanic-ossicular chain,
causes movement of the cochlear fluids. Electromechanical
transduction is a variation of electromagnetic transduction
