Magazine article Science News

A New Spin on Guiding Sound: Acoustic Device Could Cloak Submarines, Divert Loud Noises

Magazine article Science News

A New Spin on Guiding Sound: Acoustic Device Could Cloak Submarines, Divert Loud Noises

Article excerpt

An array of miniature turntables could offer a powerful new way to control the flow of sound.

The proposed device, reported in the March 20 Physical Review Letters, would channel sound waves in a protected one-way thoroughfare along its edge. The structure is an acoustic version of a hotly researched class of materials called topological insulators. As the name suggests, these materials are primarily insulators, yet they efficiently transport electrons along their periphery.

The study "shows that this rather exotic physical property can emerge in something as familiar as sound propagation," says Steven Cummer, an electrical engineer at Duke University.

For now, the design requires many moving parts and manipulates only a narrow swath of sound frequencies. But a similar structure could eventually allow engineers to redirect loud noises out of a room or perhaps to cloak submarines from sonar.

Topological insulators have exotic split personalities (SN: 5/22/10, p. 22). They both insulate, blocking the movement of electrons, and conduct, moving electrons but only in special thoroughfares along the materials' edge. All electrons with a particular spin move in the same direction; as they cruise along this one-way road, they scale bumps and leap potholes because the material's properties don't allow the particles to bounce or scatter backward--they can only move forward.

Recently, scientists have expanded the scope of topological insulators by creating materials that steer light instead of electrons (SN: 5/18/13, p. 8). Physicist Baile Zhang and colleagues at Nanyang Technological University in Singapore went further and designed an analogous device for manipulating sound. Their proposed structure is a lattice of metal rods, each encased in a cylindrical shell. The rods are sized and spaced to interfere with sound waves and confine the waves to the material's edge. …

Search by... Author
Show... All Results Primary Sources Peer-reviewed

Oops!

An unknown error has occurred. Please click the button below to reload the page. If the problem persists, please try again in a little while.