Fingerprints aren’t the only unique human identifier: The ear canal produces a particular signature based on how sounds echo or are absorbed inside it.

But that auditory John Hancock has largely been overlooked—until now.

Inspired by the pervasiveness of earbuds on college campuses, University at Buffalo computer scientist Zhanpeng Jin developed a novel way of unlocking your phone.

“We have so many students walking around with speakers in their ears,” the associate professor said in a statement. “It led me to wonder what else we could do with them.”

The answer: EarEcho, a biometric tool that uses modified wireless earbuds to authenticate smartphone users via the individual geometry of their ear canal.

A team of researchers led by Jin built their prototype from off-the-shelf products—including a pair of in-ear buds and a tiny microphone.

Scientifically speaking, when a sound is played into someone’s ear, it propagates through and is reflected and absorbed by the ear canal. This process produces a unique signature that can be recorded by a microphone.

“It doesn’t matter what the sound is, everyone’s ears are different and we can show that in the audio recording,” according to Jin. “This uniqueness can lead to a new way of confirming the identity of the user, equivalent to fingerprinting.”

The information is gathered by a built-in microphone and sent via Bluetooth to a connected smartphone, where it is analyzed.

To test their tech, Jin & Co. streamed audio samples—speech, music, etc.—to 20 people in different environmental settings (on the street, in a shopping mall) in different positions (sitting, standing, head tilted).

The model, as described in this month’s Proceedings of the ACM journal, proved roughly 95 percent effective when given one second to authenticate the listener.

That score improved to 97.5 percent during a three-second window.

EarEcho’s most obvious application is unlocking smartphones, making passcodes, fingerprints, facial recognition, and other biometrics moot.

“Think about that,” Jin said. “Just by wearing the earphones, which many people already do, you wouldn’t have to do anything to unlock your phone.”

But the computer scientist has loftier plans for the continuous monitoring of smartphone users: The passive system, he said, is ideal for situations where folks are required to verify their identity—like making mobile payments.

UB’s Technology Transfer office has filed a provisional patent application for the mechanic.

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