Scientists guide sound waves through a maze

"The ultimate goal would be to achieve the same results in three-dimensional space with light waves, which would allow us to make objects invisible," physicist Stefan Rotter said.

By Brooks Hays
Scientists guide sound waves through a maze
Scientists used interference from loudspeakers to manipulate sound waves, successfully maneuvering them around obstacles as they traveled through a long sound tube. Photo by TU Wien

July 3 (UPI) -- Scientists have successfully guided sound waves through a maze, a tube pathway complicated by a variety of obstacles.

The research could inspire new technologies for the control and manipulation of both sound waves and lightwaves.


"In principle, our technology can be applied to any type of wave," Stefan Rotter, researchers at the Institute of Theoretical Physics at TU Wien in Austria, said in a news release. "From a mathematical perspective, it is irrelevant whether we are dealing with light waves, sound waves or quantum matter waves -- acoustics experiments are, however, particularly illustrative in terms of their implementation."

In order to precisely control the path of sound waves, scientists installed loudspeakers along the insides of a sound tube measuring several feet long. The loudspeakers allowed scientists to add or subtract energy from the sound wave, effectively altering its trajectory.

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"The purpose of the loudspeakers is not ... to simply reproduce the original sound wave on the other side of the tube -- that would be too easy," said Andre Brandstötter, a doctoral student working in Rotter's lab. "The idea is to manipulate the sound wave point by point and to guide it through the tube in such a way that it always has the same strength right in front of the loudspeakers."


If a normal sound wave is passed through one end of the sound tube, almost no sound will reach the other end of the air-filled tube. The irregular obstacles prevent the sounds wave's passage.

With the help of the loudspeakers, scientists can maneuver the sound wave around the obstacles. Researchers developed a mathematical formula to determine how the sound wave's complex dispersal pattern most be augmented as it approaches each obstacle.

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Informed by the formula's solutions, the loudspeakers can be used to strengthen or weaken the sound wave locally, effectively altering its dispersal pattern.

When scientists used their new sound wave manipulation methodology, they were able to receive a perfectly undisturbed sound wave at the opposite end of the tube.

"The ultimate goal would be to achieve the same results in three-dimensional space with light waves, which would allow us to make objects invisible," Rotter said.

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