Researchers from the Ben-Gurion University of the Negev and the Weizmann Institute of Science in Israel have made this discovery. A third party can eavesdrop on a conversation if the light bulb is in close proximity to people. The bulb can transmit the audio as far as 25 meters away. The method is called as Lamphone, it requires the remote electro-optical sensors to achieve the results.
A remote electro-optical sensor analyses the changes in the light bulb’s frequency response to sound waves. The earlier discovered methods of eavesdropping on the conversation had required just a compromised smart device or smart home appliances. This method requires a regular light bulb.
The report reads, “Lamphone recovers sound optically via an electro-optical sensor which is directed at a hanging bulb.” Which means that the sensor has to be directly pointed at the light source through a telescope and a voice-to-text application. The range achieved from this method can further be increased using a larger and powerful microscope.
When the researchers tested this method, they were able to test songs as well. The apps like Shazam and SoundHound was able to recognise the songs from 25 meters away.
There are multiple shortcomings in this process. The bulb needs to be hanging from the ceiling and should be in a clear vision of the sensor. The conversation or music being played has to be found enough, causing vibration on the surface of the bulb.