Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Lego-like wall produces acoustic holograms

17.10.2016

New technology shapes sound waves for applications from speakers to ultrasound imaging

Research Triangle engineers have developed a simple, energy-efficient way to create three-dimensional acoustic holograms. The technique could revolutionize applications ranging from home stereo systems to medical ultrasound devices.


This is a close up look at the metamaterial device that can create acoustic holograms. Each grid or block contains a spiral of one of 12 various densities, each of which slows sound waves by a different amount.

Credit: Steve Cummer, Duke University

Most everyone is familiar with the concept of visual holograms, which manipulate light to make it appear as though a 3-D object is sitting in empty space. These optical tricks work by shaping the electromagnetic field so that it mimics light bouncing off an actual object.

Sound also travels in waves. But rather than electromagnetic energy traveling through space, sound propagates as pressure waves that momentarily compress the molecules they are traveling through. And just like visible light, these waves can be manipulated into three-dimensional patterns.

... more about:
»3-D »acoustic »holograms »sound wave »sound waves »waves

"We show the exact same control over a sound wave as people have previously achieved with light waves," said Steve Cummer, professor of electrical and computer engineering at Duke University. "It's like an acoustic virtual reality display. It gives you a more realistic sense of the spatial pattern of the sound field."

In a paper published Oct. 14 in Nature Scientific Reports, researchers at Duke and North Carolina State University show that they can create any three-dimensional pattern they want with sound waves. The achievement is made possible by metamaterials -- synthetic materials composed of many individual, engineered cells that together produce unnatural properties.

In this case, the metamaterials resemble a wall of Legos. Each individual block is made of plastic by a 3-D printer and contains a spiral within. The tightness of the spiral affects the way sound travels through it -- the tighter the coil, the slower sound waves travel through it.

While the individual blocks can't influence the sound wave's direction, the entire device effectively can. For example, if one side of the sound wave is slowed down but not the other, the resulting wave fronts will be redirected so that the sound is bent toward the slow side.

"Anybody can tell the difference between a single stereo speaker and a live string quartet playing music behind them," explained Yangbo "Abel" Xie, a doctoral student in Cummer's laboratory. "Part of the reason why is that the sound waves carry spatial information as well as notes and volume."

By calculating how 12 different types of acoustic metamaterial building blocks will affect the sound wave, researchers can arrange them in a wall to form any wave pattern on the other side that they want. With enough care, the sound waves can produce a specific hologram at a specific distance away.

"It's basically like putting a mask in front of a speaker," said Cummer. "It makes it seem like the sound is coming from a more complicated source than it is."

Cummer and Xie, in collaboration with Yun Jing, assistant professor of mechanical and aerospace engineering at NC State, and Tarry Shen, a doctoral student in Jing's lab, proved their sound mask works in two different ways. In the first test, they assembled a metamaterial wall that manipulated an incoming sound wave into a shape like the letter "A" about a foot away. In a second demonstration, they showed that the technique can focus sound waves into several "hot spots" -- or loud spots -- of sound, also a foot from the device.

There are existing technologies that can also produce this effect. Modern ultrasound imaging devices, for example, use phased arrays with many individual transducers that can each produce precisely controlled sound waves. But this approach has its drawbacks.

"If you've ever had an ultrasound done, you know there's a small wand attached to a much bigger machine a few feet away," said Cummer. "Not only can this setup be cumbersome, it consumes an enormous amount of power. Our approach can help produce the same effect in a cheaper, smaller system."

For the metamaterial device to work in such applications, however, each cell must be smaller than the waves it is manipulating. And for ultrasound technologies that operate in the megahertz range, this means the individual cells would have to be 100 times smaller than in the current demonstration blocks.

Cummer and Xie are looking for industry partners to show that this sort of fabrication would be possible. They are also shopping the idea around to industries that work in the kilohertz range, such as aerial sensing and imaging technologies. And of course, they're speaking with sound companies to make a single speaker sound more like a live orchestra.

"We're currently in the exploration phase, trying to determine where this technology would be useful," said Xie. "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."

###

This work was partially supported by the Multidisciplinary University Research Initiative grant from the Office of Naval Research (N00014-13-1-0631).

CITATION: "Acoustic Holographic Rendering with Two-Dimensional Metamaterial-Based Passive Phased Array," Yangbo Xie, Chen Shen, Wenqi Wang, Junfei Li, Dingjie Suo, Bogdan-Ioan Popa, Yun Jing, and Steven A. Cummer. Nature Scientific Reports, Oct. 14, 2016. DOI: 10.1038/srep35437

Media Contact

Ken Kingery
ken.kingery@duke.edu
919-660-8414

 @DukeU

http://www.duke.edu 

Ken Kingery | EurekAlert!

Further reports about: 3-D acoustic holograms sound wave sound waves waves

More articles from Interdisciplinary Research:

nachricht A new method for the 3-D printing of living tissues
16.08.2017 | University of Oxford

nachricht Bergamotene - alluring and lethal for Manduca sexta
21.04.2017 | Max-Planck-Institut für chemische Ökologie

All articles from Interdisciplinary Research >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Fizzy soda water could be key to clean manufacture of flat wonder material: Graphene

Whether you call it effervescent, fizzy, or sparkling, carbonated water is making a comeback as a beverage. Aside from quenching thirst, researchers at the University of Illinois at Urbana-Champaign have discovered a new use for these "bubbly" concoctions that will have major impact on the manufacturer of the world's thinnest, flattest, and one most useful materials -- graphene.

As graphene's popularity grows as an advanced "wonder" material, the speed and quality at which it can be manufactured will be paramount. With that in mind,...

Im Focus: Exotic quantum states made from light: Physicists create optical “wells” for a super-photon

Physicists at the University of Bonn have managed to create optical hollows and more complex patterns into which the light of a Bose-Einstein condensate flows. The creation of such highly low-loss structures for light is a prerequisite for complex light circuits, such as for quantum information processing for a new generation of computers. The researchers are now presenting their results in the journal Nature Photonics.

Light particles (photons) occur as tiny, indivisible portions. Many thousands of these light portions can be merged to form a single super-photon if they are...

Im Focus: Circular RNA linked to brain function

For the first time, scientists have shown that circular RNA is linked to brain function. When a RNA molecule called Cdr1as was deleted from the genome of mice, the animals had problems filtering out unnecessary information – like patients suffering from neuropsychiatric disorders.

While hundreds of circular RNAs (circRNAs) are abundant in mammalian brains, one big question has remained unanswered: What are they actually good for? In the...

Im Focus: RAVAN CubeSat measures Earth's outgoing energy

An experimental small satellite has successfully collected and delivered data on a key measurement for predicting changes in Earth's climate.

The Radiometer Assessment using Vertically Aligned Nanotubes (RAVAN) CubeSat was launched into low-Earth orbit on Nov. 11, 2016, in order to test new...

Im Focus: Scientists shine new light on the “other high temperature superconductor”

A study led by scientists of the Max Planck Institute for the Structure and Dynamics of Matter (MPSD) at the Center for Free-Electron Laser Science in Hamburg presents evidence of the coexistence of superconductivity and “charge-density-waves” in compounds of the poorly-studied family of bismuthates. This observation opens up new perspectives for a deeper understanding of the phenomenon of high-temperature superconductivity, a topic which is at the core of condensed matter research since more than 30 years. The paper by Nicoletti et al has been published in the PNAS.

Since the beginning of the 20th century, superconductivity had been observed in some metals at temperatures only a few degrees above the absolute zero (minus...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Call for Papers – ICNFT 2018, 5th International Conference on New Forming Technology

16.08.2017 | Event News

Sustainability is the business model of tomorrow

04.08.2017 | Event News

Clash of Realities 2017: Registration now open. International Conference at TH Köln

26.07.2017 | Event News

 
Latest News

A Map of the Cell’s Power Station

18.08.2017 | Life Sciences

Engineering team images tiny quasicrystals as they form

18.08.2017 | Physics and Astronomy

Researchers printed graphene-like materials with inkjet

18.08.2017 | Materials Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>