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MIT Developed Paper-Thin Loudspeakers That Can Be Used as Noise-Canceling Wallpaper

Noise-canceling technology was used by Ford to reduce cabin noise. While this system uses the SUV’s speakers, the researchers at MIT found a far better solution. The paper-thin speakers they developed can be applied to any surface and can turn a car’s cabin into a giant noise-canceling oasis. The revolutionary speakers require very little power to work.
MIT developed paper-thin loudspeakers 6 photos
Photo: MIT via Youtube
MIT developed paper-thin loudspeakersMIT developed paper-thin loudspeakersMIT developed paper-thin loudspeakersMIT developed paper-thin loudspeakersMIT developed paper-thin loudspeakers
Speakers can be bulky, as you know from your HiFi setup. The bigger they are, the better they sound, usually, although modern technologies can make even a tiny speaker sound like a much bigger one. The technology behind speakers is quite simple, actually. It involves a membrane attached to a coil that moves back and forth under the influence of the magnetic field when the current is applied. It’s not the most efficient way of turning electrical current into sound, requiring a certain amount of power and space to work.

Researchers at MIT’s Organic and Nanostructured Electronics Laboratory have managed to create a different kind of speaker that is as thin as a sheet of paper. Even so, it is capable of producing clear, high-quality sound, using very little power. This is an improved version, as the previous ultra-thin speakers needed to be freestanding and unencumbered to produce sound. The new manufacturing process has allowed the paper-thin loudspeakers to generate sound even when mounted on a rigid surface.

This is because the new material does not need the entire panel to vibrate. The researchers started with a sheet of lightweight PET plastic that they perforated using a laser, to which they attached a thin piezoelectric material called polyvinylidene fluoride or PVDF. By subjecting both layers to vacuum and 80 degrees Celsius heat, the piezoelectric layer was pushed through the laser-cut holes in the top layer. Think of an array of tiny dome speakers that pulse and vibrate when an electric current is applied. A PET plastic spacer was also added to ensure the domes can vibrate freely.

To have an idea of how thin the speaker array really is, you can compare it to human hair in that you need six layers to make it human hair thick. When in use, the tiny speakers move a mere half micron up and down. Thousands are needed to produce audible sounds but the researchers found out that the sound is louder when the laser-cut holes get bigger. The biggest advantage is that you only need 100 milliwatts to power a single square meter (11 sq ft) of speaker material. A regular speaker would need one full watt of electricity to produce a comparable level of sound pressure.

The thin-film loudspeaker might not be appropriate for your HiFi system just yet, but it can have countless other applications. It can be applied, for instance, to office and apartment walls, or even in a car’s or an airplane’s cabin to cancel out unwanted noises. Also, it can be used to wrap an entire car, making it easier to alert pedestrians when a silent EV is approaching. The technology is promising but to be really useful it needs to hit the market first. For that, we don't have any predictions.

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About the author: Cristian Agatie
Cristian Agatie profile photo

After his childhood dream of becoming a "tractor operator" didn't pan out, Cristian turned to journalism, first in print and later moving to online media. His top interests are electric vehicles and new energy solutions.
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