Ears Making Noise?

Did you know your ears make noise? And people want to use the noise as identification?

Called otoacoustic emissions (OAEs), the ear-generated sounds emanate from within the spiral-shaped cochlea in the inner ear. They are thought to be produced by the motion of hair cells within the outer part of the cochlea.

My hearing and speech class at MIT, 6.551, went over this phenomenon. Your ear contains an active amplifier that can also create sound. Under normal conditions the emissions are very pure tones that occur at frequencies specific to each ear. The 6.551 professors had a few interesting anecdotes about the OAEs - one knew a conductor who memorized the frequency of one of his OAEs, and used it for "perfect pitch."

IIRC, though, not everyone's ears have OAEs. Aside from the problems mentioned in the article above, the Wikipedia article goes over a few details that could hamper using OAEs for biometric passwords. Another, small issue is that your ears have different OAEs, so you'd have to calibrate any system for both ears.