Researchers at the University of Stuttgart, the University of Saarland and the Max Planck Institute for Informatics in Germany are working on SkullConduct (PDF), an authentication system that uses a bone conduction speaker and mic on your head to identify you. Hooked up to a modified Google Glass, it works by playing a one-secong-long audio clip through its speaker and then captures the sound after it's traveled through the user's skull.
