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Standard headphones can identify you by your unique ear canals

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Headphones can be bought with built-in microphones, touch-sensitive buttons, motion sensors and even heart rate monitors. But researchers have found a way to bring all these features to any existing pair of standard headphones regardless of age or cost. The technique could replicate the advantages of smart headphones without the cost and environmental impact of producing new devices – and they could even be used to eavesdrop on a conversation or verify the identity of the wearer.

The tiny speakers inside headphones convert electrical signals from a smartphone or …