Researchers can make headphones leak audio through a wall, but the 30-meter claim has a few caveats
Encryption can't stop InjectEave because the audio leaks after it's been decoded, but it does have its limitations.
Researchers from Hong Kong University of Science and Technology (HKUST) and Hong Kong Polytechnic University (HK PolyU) have demonstrated a method called InjectEave that allows audio from headphones, desk phones, and smart-home devices to be broadcast through walls. The technique, presented at USENIX Security 2026, transmits a radio carrier signal into the device and uses nonlinear components within the device to leak the audio.
This method bypasses encryption and can recover audio from up to 30 meters away, including through walls, although it requires specialized and noticeable equipment. The attack targets the device's analog path after decoding, making it immune to digital defenses. The researchers used a software-defined radio, two antennas, a spectrum analyzer, and a laptop to demonstrate the technique, which successfully captured audio from a USRP B210 device, a Siglent spectrum analyzer, and a laptop.
While the threat is significant, it can only capture audio, not speech. The researchers have reported their findings to the manufacturers but have withheld specific frequencies and stripped injection control logic from their released code. No software update can fix the analog leak, limiting its practical abuse cases.
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