In our increasingly noisy world, it is difficult to find some quiet time. Now, a team of mechanical engineers at Boston University has developed a new device specifically designed to block up to 94% of incident sound waves while still letting air through.
Current technology is very effective in blocking sound. The walls of the concert hall or recording studio are covered with thick cladding, etc., which can eliminate external noise, and the newer surface can work in the same way in a small space. Either way, this will not generate too much airflow. Therefore, the Boston team set out to design an acoustic metamaterial that can effectively block sound without blocking the passage of air.
The researchers said: “The sound is caused by tiny disturbances in the air. So our goal is to silence those tiny vibrations. If we want the interior of the structure to be open-air, then we must remember that this will Ways of sound transmission. "
Their design is a 3D printed ring device that meets some very precise mathematical standards. The shape is specifically designed to interfere with incoming sound waves and cause them to bounce back the way they came. The material in the outer ring coils like a spiral, reducing the sound that can pass through the open center.
To test this device, the researchers placed a prototype at the end of the PVC pipe and connected the speakers to the other end. The loudspeaker emits white noise through the pipe, but when viewed from the outside, the human ear cannot hear it. When the metamaterial was removed, the tone suddenly reverberated throughout the room. According to the researchers, the device can block 94% of the sound.
"The moment we first placed and removed the silencer ... it was actually day and night," said the study's co-author Jacob Nikolajczyk. "We have been seeing these results in computer modeling for months-but it is one thing to see the simulated sound pressure level on a computer, and the other is to hear the effects of it yourself."
A similar design has been done before, including a window that reduces noise by 30 dB, but this new window sounds more effective. Others use active noise cancellation technology, which is common in headphones, but this requires power and a processor to process the digital. In the future, this new device may be more suitable for more places.
Researchers say that this device can have many applications in the real world in situations where sound needs to be blocked but airflow is not obstructed. These rings can be placed around the exhaust vents of jet engines, under fans on drones, or in the vents of heating and cooling systems in buildings. And it does not necessarily have to be completely round.
"We can design the shape as a cube or hexagon, anything real," said the study's co-author Reza Ghaffarivardavagh. "Our structure is very light, open and beautiful. Each piece can be used as a tile or brick to expand the scale and build a permeable wall that can eliminate sound."
The research was published in the journal Physical Review Letters.
What is the AHD Four in One CCTV Kit? The AHD Four in One CCTV Kit / AHD CCTV Kit / AHD CCTV Kit HD / AHD CCTV Kit Near Me / AHD CCTV Kit Youtube/ AHD Kit AHD CCTV System is an importable part of the CCTV Kit, and this kind of CCTV Kit is also widly applied to the many fields.
So what about the advantages of the AHD Four in One CCTV Kit?
AHD Four in One CCTV Kit is the combination of the AHD Four in One Cameras and the Digital Video Recorder. Let me introduce you the 2 parts respectively.
The AHD Four in One Camera, also called the Analog High Definition Camera, one type of the Analog Camera , contains 4 video formats, and they are AHD,TVI,CVI,and CVBS respectively. The AHD Four in One Camera can transmit the ultra-long distant (500 meters) high-definition analog signal(resolution above 720P is High Definition, also called the HD ) via the ordinary video cable or the 75-5 coaxial cable.The AHD Four in One Camera adopts the advanced Y/C signal separation and analog filtering technology, which can effectively reduce color noise in the high-frequency area and improve the image restoration. Besides, compared with the traditional analog high-definition camera, the image resolution of the AHD Four in One Camera has a great improvement and the highest definition can reach up to the equal level to the network HD 1080P.
The Digital Video Recorder, also called the DVR , is the video storage device(a computer system for image storage and processing) via the hard disk recording. The Digital Video Recorder has the functions of long-term image recording, voice recording, remote monitoring and control of images/voices. In terms of the image processing, image storage, retrieval, backup, network transmission, and remote control, the Digital Video Recorder is the far superior to the analog monitoring equipment because of the adoption of the digital recording technology.
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What about the disadvantages for the AHD Four in One CCTV kit?
The AHD Four in One CCTV Kit is wired and it is not so convienient as the Wireless CCTV Kit in some applications, but the AHD Four in One CCTV Kit is stable and cheap in some degree.
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