Scientists at MIT have developed a type of soundproof sheet that can not only cancel or block the sound, but it will even reflect the sound back at the maker. This new development could prove exceptionally useful in apartments with thin walls.
The new development builds off of previous research by MIT researchers that sought to create sheets of fabric that could be converted into microphones. However, this newest project turns them into speakers instead. The researchers say you need a thin sheet of fabric — silk seems to work the best, which can then be adhered to a single piezoelectric fiber.
When an electric current runs through the piezoelectric fiber, the material deforms. And, when the current fluctuates rapidly, the fiber rapidly moves back and forth between its regular state and the deformed state, allowing vibrations to travel through the material. These vibrations allow the fiber to displace air and even produce sound waves, creating the foundation for a soundproof sheet.
To achieve the soundproofness, though, you also have to deliberately make the fibers out of phase with the offending sound waves. This allows them to cancel the other waves out. It’s a method similar to how noise-canceling technology in headphones works.
During tests, the researchers were able to get the soundproof sheet to emit up to 70 decibels of sound while reducing the offending sounds by up to 37 decibels. And that was just with an 8 × 8 centimeter square of silk. While the first part of the equation here works best in small spaces, the second part could be utilized in larger spaces to virtually soundproof an area.
This could prove exceptionally useful in bedrooms within apartments with thin walls, as an electric current can be put through the sheet, forcing the piezoelectric fibers to hold the material still, which would essentially keep any sound from passing through. This creates a soundproof sheet that can help block our noisy neighbors, or even stop your own sounds from exiting the room.
A paper on the discovery was published in Advanced Materials. Researchers with MIT continue to do amazing things, including creating concrete that can store energy.
