Researchers in China have developed InjectEave, an electromagnetic side-channel attack that can recover audio from headphones and other devices from a distance. By actively injecting radio-frequency signals rather than passively detecting weak emissions, attackers may be able to eavesdrop through walls, creating potential risks for private conversations and household activity monitoring.

The technique exploits non-linear components such as amplifiers and converters, using commodity radio equipment to modulate otherwise faint audio signals. Tests on 11 commercial headphones, phones, smart fans and lamps found most could be attacked from more than two metres away; intelligible headphone audio was recovered at up to 30 metres with an amplifier, although typical demonstrated ranges were around one to six metres.