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These space coiling bricks act to slow down sound waves, meaning that they can be transformed into any required sound field. Credit: The University of Sussex

A team of scientists have developed a new, sound manipulating material that could transform medical imaging and personal audio.

Researchers from the University of Sussex and Bristol have developed the new super-material, which can bend, shape and focus sound waves that pass through it.

Finely shaped sound fields are used in medical imaging and therapy, as well as a variety of consumer products, including audio spotlights and ultrasonic haptics.

The research team was able to assemble a metamaterial layer out of lots of small bricks that each coil up space. The space coiling bricks act to slow down the sound, which means that incoming sound waves can be transformed into any required sound field.

This method is viewed as a simple and inexpensive way to create shaped sound waves using acoustic metamaterials.

Gianluca Memoli, Ph.D., from the Interact Lab at the University of Sussex and lead author of the study, explained the intent of the researchers.

“Our metamaterial bricks can be 3D printed and then assembled together to form any sound field you can imagine,” Memoli said in a statement. “We also showed how this can be achieved with only a small number of different bricks.

“You can think of a box of our metamaterial bricks as a do-it-yourself acoustics kit.”

Some of the applications include using large versions of the metamaterial layers to direct or focus sound to a particular location and form an audio hotspot. Scientists can also use smaller versions to focus high intensity ultrasound to destroy tumors deep within the body. A metamaterial layer could be tailor-made to fit the body of a patient and tuned to focus the ultrasound waves where they are most needed.

In both these scenarios the layer could be fitted to existing loudspeaker technology and be made rapidly and cheaply.

Professor Sriram Subramanian, head of the Interact Lab at the University of Sussex, added that the metamaterial can be controlled.

“We want to create acoustic devices that manipulate sound with the same ease and flexibility with which LCDs and projectors do to light,” Subramanian said in a statement. “Our research opens the door to new acoustic devices combining diffraction, scattering and refraction and enables the future development of fully digital spatial sound modulators, which can be controlled in real time with minimal resources.”

Bruce Drinkwater, professor of Ultrasonics at the University of Bristol, explained what the discovery could lead to.

“In the future I think there will be many exciting applications of this technology,” Drinkwater said in a statement. “We are now working on making the metamaterial layers dynamically reconfigurable.

“This will mean we can make cheap imaging systems which could be used either for medical diagnostics or crack detection,” he added.         

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