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Noise-Canceling Windows Could Work Even When They're Open

Have you ever had to deal with a neighbor's house party raging into the wee hours of the morning? Or an obnoxious motorcycle revving its engine while it blows past your front door? How about construction crews starting roadwork at 7 in the morning? Well, researchers may have come up with a solution to these problems, and the technology will be familiar to anyone who loves their noise-canceling headphones.

Come On, Feel the Noise

You might not think of noise pollution as a significant problem, but the World Health Organization, the Centers for Disease Control, and researchers worldwide have warned of its potential effects on hearing and overall health. Too much noise can trigger an increase in blood pressure and heart rate and can cause sleep disturbances and reductions in quality of life — not to mention that it's downright annoying.

Of course, most outside noise leaks in through the windows, so you could fix the problem by just not having any windows. But nobody wants to live in a cave, not to mention the multitude of benefits you get from exposure to natural light. You could always buy extra-thick soundproof windows, but there's another problem there: they have to be closed if you want them to actually block sound. That's why a team of Singapore researchers looked at noise-canceling technology as a possible solution.

Active noise-canceling systems not only block sound, but also actively "cancel" sound by emitting opposing sound waves. These devices actively listen to incoming noise via a built-in microphone, then algorithms analyze the waveform and generate an inverted version that the speakers play back. When the two sounds converge, the opposing sound waves cancel each other out in a phenomenon known as destructive interference. Ironically, an active noise-canceling device is technically making more noise — it just counteracts the external noise you don't want to hear, producing silence in its wake.

Code Talker, Meet Quiet

Researchers working on the Smart Campus initiative at Nanyang Technological University, Singapore have been building cutting-edge technology on campus — think delivery drones, cafeteria robots, and universal electronic passes — with the ultimate aim of making life easier for society as a whole. To solve the noise pollution problem, they decided to try applying active noise-canceling technology to entire windows. They built a prototype system that included a grid of gadgets that each contained a microphone, a speaker, and a processing unit. To test the system, the team built a replica room with windows and doors inside a soundproof chamber. They attached the prototype to the window and used a speaker to play recorded sounds of everyday annoyances like construction work, jet engines, and passing trains.

According to the researchers, the system is able to reduce up to 50 percent of noise pollution that enters buildings — even when the windows are wide open. "Compared to noise cancellation headphones, what we have achieved is far more technically challenging as we needed to control the noise in a large open area, instead of just around the ear," said Professor Gan Woon Seng, the lead researcher on the project. "Our innovation not only computes the right amount and type of 'anti-noise' to emit, but also does it faster than the detected noise can reach inside the building."

Right now, the major drawback is aesthetic: the current prototype requires around 24 devices to be mounted on the window grille to control the noise in a large area with absolute efficiency. The team's next step is to achieve the same results using fewer devices, as well as to make sure the system works properly even when the window is open. They're using machine learning technology to differentiate "bad" sounds from good ones and eliminate the worst offenders. That's potentially great news for the next time you catch construction crews tearing up your street at the crack of dawn.

"We are currently finding ways to improve the technology further so that it can be used not only at window grilles with large openings, but also provide a cost-effective solution that can be easily installed and replaced," Professor Gan said. "Ultimately, we aim to integrate this technology into window grilles that can help mitigate urban noise pollution conveniently."

Want to up your headphone game? Try Bose QuietComfort 35 wireless headphones II with active noise-canceling technology. If you make a purchase through that link, then Curiosity will get a share of the sale.

Written by Cody Gough May 24, 2018

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