Consider all the tools that modify how light is transmitted and received: lasers direct light in a tightly focused beam and telescopes let us focus on an area far away. While there are certainly ways to modify sound, these techniques are not nearly as developed as their light counterparts.
With hopes of changing that, researchers from the University of Sussex and the University of Bristol have been working with metamaterials—normal materials like plastic, paper, wood or rubber with an internal structure designed to manipulate sound waves—to build acoustic lenses.
The team demonstrated the first dynamic metamaterial device with the zoom objective of a varifocal for sound, as well as create a collimator capable of transmitting sound as a directional beam from a standard speaker.
The lenses are attached to the collimator, and can be used to direct sound from a speaker or two can be employed together to construct an adjustable focus system. Focal length is regulated by the distance between the two lenses, which is controlled by an Arduino Nanoand a single stepper motor mounted to an adjustable rail.
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