The Glowworm Attack, as the discovery is called, follows similar research from the university published in 2020 that found an electro-optical sensor paired with a telescope was able to decipher the sounds in a room. Sound waves bounced off a hanging light bulb create nearly imperceptible changes in the lighting in the room. With the Glowworm Attack, the same technology that made Lamphone possible is repurposed to remotely eavesdrop on sounds in a room again, but using a completely different approach that many speaker makers apparently never even considered.
Pairing the sensor with a telescope allowed the security researchers at Ben-Gurion University to successfully capture and decipher sounds being played by a speaker at distances of up to 35 meters, or close to 115 feet. The results aren’t crystal clear (you can hear the remote recordings the researchers made on Ben Nassi’s website), and the noise increases the farther away from the speaker the capture device is used, but with some intelligent audio processing, the results can undoubtedly be improved.