Acoustic Cloaking Device Hides Objects From Sound: Duke University Research

Engineers from Duke University have developed world’s first 3D acoustic cloaking device. The acoustic cloaking device is built out of several sheets of paper and number crunching. It works in three dimensions which reroutes the sound waves and creates an impression that the device and anything beneath it does not exist. Professor Steven Cummer from the of Electrical and Computer Engineering Department at the University explained that when the cloak is kept around the object, sound waves behave as if there’s just a flat surface in their path.

The field of metamaterials which is a combination of natural materials in repeating patterns and achieves unnatural properties is used. The new device which looks just like a pyramid and consisting of plastic and air manipulates the sound waves. The acoustic cloaking device gives the illusion by altering the trajectory of waves. The waves could not reach the surface beneath and hence travels a shorter distance and its speed is slowed to compensate.

For testing the new device, these researchers used a sphere covered with cloak and recorded short bursts of sound from various angles. The behavior of the waves were mapped using a microphone and produced videos of waves through air. The videos were then compared with those which were created by keeping the sphere without cloak. The results proved that the waves behaved as if they were reflected from an empty surface. Though the demonstration is simple, researchers believe that the concept could have wide application. Sound waves behave exactly the same way underwater as they behave in air, thus making it possible for sonar avoidance to become one of the uses. Also, this is useful wherever acoustics are used.

Share with us in comments what more applications you can think of.

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