In a research paper published this week, academics detailed a novel method of recovering conversations and audio recordings by observing vibrations in a light bulb.
The technique, which they named Lamphone, revolves around the principle that objects vibrate when soundwave hits their surface.
When this happens in a light bulb, academics say the vibrations also create small flickers in light emissions. They say that by using powerful sensors, they can record the light variations and reverse-engineer the sound waves that hit the light bulb's surface.
But like any novel surveillance technique, Lamphone has its advantages and limitations.
The most obvious is that attackers need a direct line of sight to the light bulb in a room or public space. Light bulbs protected by decorative covers or other constructs are safe from this attack, and so are conversations that take place in rooms without windows.
However, once a line of sight to a light bulb is available, academics say an attacker can use tools like a telescope and an electro-optical sensor to record light variations in the light bulb from large distances and don't necessarily have to be close to their targets.
In experiments they carried out for their paper, they said they successfully recovered sound and conversations from 25 meters (82 feet) away.
"This range can be amplified with proper equipment (bigger telescope, 24/32 bit ADC, etc.)," the research team said.
In their experiment, the research team said it was successful in recovering both human speech and room effects -- such as music played in the background (see demo below for an example).
A disadvantage is that conversations need to be loud enough to generate vibrations, or speakers need to be close enough to the light bulb.
However, having the ability to eavesdrop on corner offices from tens of meters