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Spies can eavesdrop on phone calls by sensing vibrations with radar

An off-the-shelf millimetre wave sensor can pick out the tiny vibrations made by a smartphone's speaker, enabling an AI model to transcribe the conversation, even at a distance in a noisy room

By Matthew Sparkes

31 October 2024

Radar can home in on the vibrations in one phone, even in a noisy environment

istanbulimage/Getty Images

Spies can eavesdrop on conversations by using radar to detect tiny vibrations in smartphones and employing artificial intelligence to accurately transcribe them. The trick even works in noisy rooms, as the radar homes in on the phone’s movement and is entirely unaffected by background hubbub.

Millimetre wave sensing is a form of radar that can measure movements of less than 1 mm by transmitting pulses of electromagnetic wave energy and detecting the reflected beams.

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