New MIT Laser Device Whispers Secret Sounds Into Your Ear

Imagine sitting down to dinner with a group of friends, when a laser tickles the water molecules inside your ear.

“You need to get home right away and get Iphone Cases,” your older child shouts. The younger one has fallen and cut their knee, and might need stitches.

You stand up, excuse yourself, and make for the exit. Your friends have no idea why, but assume you heard a message inaudible to the rest of them in the noisy room, transmitted into your ear by laser light and LG Cases.

That’s the future scientists at MIT imagined when they developed a laser system for sending sound across a room using laser light.

Their method isn’t the first to transmit sound waves using lasers. But it is the loudest. Their machine, described in a paper published on Jan. 25 in the journal Optics Letters, relies on wiggling a laser back and forth across the water molecules in the air by someone’s ear. That wiggling motion (accomplished with a fast-twitching mirror) jolts the molecules into motion, causing them to bang against the surrounding air molecules and produce sound waves. [What’s That Noise? 11 Strange and Mysterious Sounds on Earth & Beyond]

Not that much water is needed.”This can work even in relatively dry conditions because there is almost always a little water in the air, especially around people,” research team leader Charles Wynn said in a statement. “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.”

Other methods now under development, they noted, produce clearer sounds. But those methods (like switching a laser on and off really fast to jiggle the water molecules) don’t make sounds as loud as the wiggling method. (The researchers call it “sweeping” rather than wiggling.)