Lego-like Wall Produces Acoustic Holograms

Most people know about visual holograms and how they are created using electromagnets to manipulate light. The effect of this manipulation is the appearance of a 3D structure floating in mid air. What most people don't know is that the same manipulation can be applied to sound waves. Sound also travels in waves, like light, and compresses molecules it travels through.  Steve Cummer, professor of electrical and computer engineering at Duke University has found a way to make structures that manipulate sound waves to make them into 3D patterns. The structures that are used are specifically engineered cells that, when together, form unnatural properties. In the case of this study the cells rearrange a wall legos. Each lego is specially made by a 3D printer and have spirals coming out of the bottom. The tightness of the spiral effects the way sound travels through the block, ex. the tighter the coil the slower the sound travels through it. Although the individual lego bricks can't direct the sound, the entire device can. By controlling the sound waves, scientists can make specific patterns from specific distances. The process requires a monstrous amount of power and the equipment is very large. Scientists right now are focusing on condensing the material to be smaller and consume less power. They hope to make the device function in megahertz which would mean the cells would have to be 100 times smaller than they already are. The people working on this project now think it's possible but need funding and partners to help make this idea a reality. Other work they are doing is trying to get a company to make a speaker that sounds like a live orchestra. Xie, a doctoral student in Cummer's laboratory explains that "We're currently in the exploration phase, trying to determine where this technology would be useful. Any scenario where your goal is to control sound, this idea could be deployed. And it could be deployed to make something totally new, or to make something that already exists better, simpler or cheaper." With these strives in sound manipulation and cell engineering regular sound systems are a thing of the past. These discoveries have shown that sound is something much more than we had previously perceived it to be. Only time will tell what discoveries will come next in the field of 3D sound.