Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Caltech engineers develop 1-way transmission system for sound waves

27.07.2011
While many hotel rooms, recording studios, and even some homes are built with materials to help absorb or reflect sound, mechanisms to truly control the direction of sound waves are still in their infancy.

However, researchers at the California Institute of Technology (Caltech) have now created the first tunable acoustic diode-a device that allows acoustic information to travel only in one direction, at controllable frequencies.


The nonlinearity and asymmetry present in this chain of compressed spheres can transform vibrations of one frequency, applied at one end of the chain, to vibrations with broadband frequency content leading to rectification. The amplitude of the vibrations are shown by the height of the peaks. Credit: Chiara Daraio / Caltech

The mechanism they developed is outlined in a paper published on July 24 in the journal Nature Materials.

Borrowing a concept from electronics, the acoustic diode is a component that allows a current—in this case a sound wave—to pass in one direction, while blocking the current in the opposite direction. "We exploited a physical mechanism that causes a sharp transition between transmitting and nontransmitting states of the diode," says Chiara Daraio, professor of aeronautics and applied physics at Caltech and lead author on the study. "Using experiments, simulations, and analytical predictions, we demonstrated the one-way transmission of sound in an audible frequency range for the first time."

This new mechanism brings the idea of true soundproofing closer to reality. Imagine two rooms labeled room A and room B. This new technology, Daraio explains, would enable someone in room A to hear sound coming from room B; however, it would block the same sound in room A from being heard in room B.

"The concept of the one-way transmission of sound could be quite important in architectural acoustics, or the science and engineering of sound control within buildings," says Georgios Theocharis, a postdoctoral scholar in Daraio's laboratory and a co-author of the study.

The system is based on a simple assembly of elastic spheres—granular crystals that transmit the sound vibrations—that could be easily used in multiple settings, can be tuned easily, and can potentially be scaled to operate within a wide range of frequencies, meaning its application could reach far beyond soundproofing.

Similar systems have been demonstrated by other scientists, but they all feature smooth transitions between transmitting and nontransmitting states instead of the sharp transitions needed to be more effective at controlling the flow of sound waves. To obtain the sharp transition, the team created a periodic system with a small defect that supports this kind of quick change from an "on" to an "off" transmission state. According to Daraio, this means the system is very sensitive to small variations of operational conditions, like pressure and movement, making it useful in the development of ultrasensitive acoustic sensors to detect sound waves. The system can also operate at different frequencies of sound and is capable of downshifting, or reducing the frequency of the traveling signals, as needed.

"We propose to use these effects to improve energy-harvesting technologies," she says. "For example, we may be able to scavenge sound energy from undesired structural vibrations in machinery by controlling the flow of sound waves away from the machinery and into a transducer. The transducer would then convert the sound waves into electricity." Daraio says the technology can also shift the undesired frequencies to a range that enables a more efficient conversion to electricity.

The team plans to continue studying the fundamental properties of these systems, focusing on their potential application to energy-harvesting systems. They also believe that these systems may be applicable to a range of technologies including biomedical ultrasound devices, advanced noise control, and even thermal materials aimed at temperature control.

"Because the concepts governing wave propagation are universal to many systems, we envision that the use of this novel way to control energy might enable the design of many advanced thermal and acoustic materials and devices," says Daraio.

The Nature Materials paper is titled "Bifurcation-based acoustic switching and rectification." Nicholas Boechler, a former Ph.D. student at Caltech, is also an author on the study.

The research was supported by the National Science Foundation, the Office of Naval Research, and the A. S. Onassis Benefit Foundation.

Deborah Williams-Hedges | EurekAlert!
Further information:
http://www.caltech.edu

More articles from Materials Sciences:

nachricht Researchers shoot for success with simulations of laser pulse-material interactions
29.03.2017 | DOE/Oak Ridge National Laboratory

nachricht Nanomaterial makes laser light more applicable
28.03.2017 | Christian-Albrechts-Universität zu Kiel

All articles from Materials Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: A Challenging European Research Project to Develop New Tiny Microscopes

The Institute of Semiconductor Technology and the Institute of Physical and Theoretical Chemistry, both members of the Laboratory for Emerging Nanometrology (LENA), at Technische Universität Braunschweig are partners in a new European research project entitled ChipScope, which aims to develop a completely new and extremely small optical microscope capable of observing the interior of living cells in real time. A consortium of 7 partners from 5 countries will tackle this issue with very ambitious objectives during a four-year research program.

To demonstrate the usefulness of this new scientific tool, at the end of the project the developed chip-sized microscope will be used to observe in real-time...

Im Focus: Giant Magnetic Fields in the Universe

Astronomers from Bonn and Tautenburg in Thuringia (Germany) used the 100-m radio telescope at Effelsberg to observe several galaxy clusters. At the edges of these large accumulations of dark matter, stellar systems (galaxies), hot gas, and charged particles, they found magnetic fields that are exceptionally ordered over distances of many million light years. This makes them the most extended magnetic fields in the universe known so far.

The results will be published on March 22 in the journal „Astronomy & Astrophysics“.

Galaxy clusters are the largest gravitationally bound structures in the universe. With a typical extent of about 10 million light years, i.e. 100 times the...

Im Focus: Tracing down linear ubiquitination

Researchers at the Goethe University Frankfurt, together with partners from the University of Tübingen in Germany and Queen Mary University as well as Francis Crick Institute from London (UK) have developed a novel technology to decipher the secret ubiquitin code.

Ubiquitin is a small protein that can be linked to other cellular proteins, thereby controlling and modulating their functions. The attachment occurs in many...

Im Focus: Perovskite edges can be tuned for optoelectronic performance

Layered 2D material improves efficiency for solar cells and LEDs

In the eternal search for next generation high-efficiency solar cells and LEDs, scientists at Los Alamos National Laboratory and their partners are creating...

Im Focus: Polymer-coated silicon nanosheets as alternative to graphene: A perfect team for nanoelectronics

Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are less stable. Now researchers at the Technical University of Munich (TUM) have, for the first time ever, produced a composite material combining silicon nanosheets and a polymer that is both UV-resistant and easy to process. This brings the scientists a significant step closer to industrial applications like flexible displays and photosensors.

Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

International Land Use Symposium ILUS 2017: Call for Abstracts and Registration open

20.03.2017 | Event News

CONNECT 2017: International congress on connective tissue

14.03.2017 | Event News

ICTM Conference: Turbine Construction between Big Data and Additive Manufacturing

07.03.2017 | Event News

 
Latest News

NASA laser communications to provide Orion faster connections

30.03.2017 | Physics and Astronomy

Reusable carbon nanotubes could be the water filter of the future, says RIT study

30.03.2017 | Studies and Analyses

Unique genome architectures after fertilisation in single-cell embryos

30.03.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>