A team of researchers from the University of Texas has created the world's first one-way acoustic circulator, refuting the theory that "if you can hear, then you can hear." The created device is quite compact and, controlling the direction of sound waves, allows the user to hear the sound, but not to be heard.
According to the fundamental theory, all physical waves have the property of symmetry. This means that if a wave moves in a certain direction, it can move in the opposite direction. In the case of radio waves, engineers have long been able to circumvent this rule, using magnetic materials that orient electrons in one direction. Now, scientists decided to try a similar technique for acoustic vibrations.
A classic circulator is a device with three ports in which a signal is sent sequentially from one port to another. In this case, when one port is not used, it works as an isolator, blocking the return of the sent signal.
A team of experts applied this design to use sound waves. A fan was turned into the circulator at a certain speed, the purpose of which was to inject air. All sounds passing through the resonator were directed through one of three tubes. At the end of each of them was a microphone. At the same time the air inside created a stream in which the sound could move only in one direction.
For example, a person at the end of the first tube could send a signal to the listener at the second tube, but would not hear the answer. In this case, the answer of the second user was able to hear the third.
Such devices will work as a sound one-way mirror and can be used to listen to people. In this case, the spy can hear the whole conversation without fear of being heard.
The researchers themselves believe that this technology can be widely used in the field of insulation of premises, such as sound studios, as well as sound insulation of highways, airplanes, submarines.
Based on gizmag.com
The article is based on materials .
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