"Lamphone", a new technology for long-distance eavesdropping, was discovered by researchers, without the need to penetrate anything or resort to installing devices in the rooms.
The new technology allows anyone with a laptop and a set of equipment - just a telescope and an electric optical sensor - to hear any sounds in a room hundreds of feet away in real time.
This can be done by observing the tiny vibrations these sounds generate on the glass surface of a light bulb inside the room.
By measuring the slight changes in light output from the bulb caused by these vibrations, the researchers showed that the sound could be captured clearly enough to discern the contents of the conversations.
And any sound in the room can be retrieved according to aitnews, without the need to penetrate anything and without a device in the room, but there is a need to have a sight line to the suspended lamp.
In their experiments, the researchers placed a series of telescopes about 25 meters from the target office light bulb, and placed in front of the lens each telescope an electro-optical sensor (Thorlab PDA100A2).
They used an analog-to-digital converter to convert electrical signals from this sensor to digital information, and while speaking in the remote room they fed the captured information by preparing a laptop computer that analyzed the readings.
The researchers found that the minute vibrations of the light bulb in response to sound were recorded as measurable changes in the light captured by the sensor through each telescope.
After processing the signal through a noise filtering program, they were able to reconstruct the sound recordings in the room with remarkable accuracy.
But the technology faces some limitations. Researchers have used a suspended lamp in their tests, and it is not clear whether the fixed lamp or ceiling lamp vibrates enough to derive the same type of acoustic signal.
The audio conversations they used were also louder than normal human conversation, and the speakers were close enough to the light bulb, while lifting it to its maximum capacity.
But the team notes that they also used a relatively inexpensive optical electrical sensor and analog converter, and they could upgrade this equipment to capture quieter conversations.