Device to adjust sound in the direction

Researchers at the California Institute of Technology (Caltech), USA, have successfully built the first audio diode device, a device that adjusts sound waves in one direction, at the right frequency. .

While many hotel rooms, record labels, and even some houses are built with absorbing materials or sound feedback, mechanisms that control the direction of sound waves are a real need. indispensable.

The research results are published in the journal Nature Materials , issued July 24, 2011.

This is the shoulder concept borrowed from the electronic field: a sound diode is a device that helps to adjust sound waves in one direction, while preventing sound feedback in the opposite direction. " We exploit the physical mechanism that causes transitions between transmitting and blocking sound waves of this audio diode ," says Chiara Daraio, professor of aeronautics and applied physics. at the California Institute of Technology (Caltech), USA, and the lead author of the study. " Using experiments, simulations, and predictive analysis, for the first time, we have shown that transmitting sound waves in one direction is possible, within the audio frequency range ."

The nonlinear and asymmetric appear in the series of elastic spherical crystalline particles, changing the vibration of a frequency, acting on one end of the chain, creating vibrations with broadband frequency to refine .The amplitude of the oscillations is shown by the height of the tip.

This new sound insulation mechanism gives the idea of ​​applying it to real life. Imagine two rooms labeled Room A and Room B. This new technology, Daraio explains, will allow someone in room A to hear the sounds coming from room B. However, it will stop those members in room B cannot hear the sounds themselves.

" The concept of transmitting sound waves in a certain direction is an important discovery in architectural acoustics, or for the science of controlling and coordinating sound in buildings ," according to Georgios Theocharis, He practiced at Daraio's laboratory and co-authored the study.

The system operates based on a simple assembly of elastic spherical crystalline particles, which can transmit sound and vibration, which enables the device to be used in many applications: Adjustable Easily and extensively upgrade works in many different frequencies, the meaning of the application can far surpass the soundproof ability.

Similar systems have been tested by other scientists, but all devices have a smooth transition between the two states: transmitting and preventing sound wave transmission, the necessary sharp transition. More effective in controlling the flow of sound waves. To achieve this sharp transition, the team created a periodic system with a small defect to support rapid change: " turn on " from an " off " state of the sound propagation bar. According to Daraio, that means the system is very sensitive to small changes in operating conditions, such as pressure and movement, making it useful in developing super-sensitive sound sensors to detect sound waves. The system can also operate at different audio frequencies and is capable of increasing or decreasing the frequency of sound wave signals emitted when needed.

" We propose using these effects to improve energy collection technologies ," she said. " For example, we can collect energy from the vibrations of unwanted sounds, in machines by controlling the flow of sound waves from the machinery that is fed into the transducer. will turn sound waves into electricity . " Daraio thinks that technology can also help to adjust unwanted frequencies to a range that allows it to be more efficient in converting sound waves into electricity.

The team is planning to continue to study the basic properties of this system, focusing on the potential application of the device to harvest energy from various sources of sound waves. They also believe that this system can be applied to a variety of technological devices such as biomedical ultrasound, noise control, and even thermal materials for temperature control purposes.

"The concept of controlling the transmission of sound waves in one direction is common for many systems, we envision the use of new energy-gathering methods that can design many materials and thermal devices. and advanced sound , "Daraio added.

The article in the journal Nature Materials , published on July 24, 2011, is titled " Refine and tune sound waves in a way ." Nicholas Boechler, a former Ph.D. intern at the California Institute of Technology (Caltech), USA, is also the co-author of the study.

The research was funded by the US National Science Foundation, the Naval Research Agency and the Alexander Welfare Foundation - Onassis.