Researchers from the Massachusetts Institute of Technology (MIT) have just developed something seemingly out of a James Bond movie: a laser capable of beaming an audio message directly into the ear of a targeted person.
The technology makes use of the photoacoustic effect, which occurs when a material forms sound waves after absorbing light. In this case, the material utilized is water vapor that's naturally floating in the air, according to a press release.
Amazingly, anyone's ear that crosses one of these laser beams should hear the intended audio message at a conversational volume, even if it's in a crowded room with other loud ambient sound. Furthermore, only the person at the end of the beam will hear the message; anyone else in the room won't hear a thing.
“Our system can be used from some distance away to beam information directly to someone's ear,” said research team leader Charles M. Wynn. “It is the first system that uses lasers that are fully safe for the eyes and skin to localize an audible signal to a particular person in any setting.”
Prototypes of the technology have demonstrated successful transmission of audio messages to an individual standing 2.5 meters away from the laser source, but researchers believe the system can be easily scaled up to transmit over much longer distances. Furthermore, by tweaking the length of the laser sweeps, researchers think they can make it so that only individuals standing at particular lengths from the source will be capable of hearing the message correctly. This will make it possible to target specific individuals rather than transmitting to any ear that crosses the beam.
And even though the method requires water vapor in the air, it should still work even under very dry conditions.
“This can work even in relatively dry conditions because there is almost always a little water in the air, especially around people,” said Wynn. “We found that we don't need a lot of water if we use a laser wavelength that is very strongly absorbed by water. This was key because the stronger absorption leads to more sound.”
While this technology could certainly add intrigue to many a spy mission, it could also have a slightly more nefarious purpose. For instance, imagine a world where advertisers can target you specifically, with personalized messages that only you can hear. And you can't turn the messages off because the technology doesn't require any sort of receiver that you can toggle.
It would certainly be a strange experience to suddenly hear voices directly whispering into your ear while walking about in the world. Having personalized voices in your head would no longer be a sign of mental pathology; it would become our new, omnipresent social reality.
“We hope that this will eventually become a commercial technology,” said Ryan M. Sullenberger, first author on the paper published in Optic Letters. “There are a lot of exciting possibilities, and we want to develop the communication technology in ways that are useful.”