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Scientists say you can cancel the noise but keep your window open



Car alarms, jackhammer, a drunk argument and the rumble of train # 7 that drives over us. It is the wonderful urban symphony that flows into a typical New York apartment building day and night.

Sure, closing the window can help, but it’s about your natural ventilation.

What if there was a technology that could suppress the annoying noise, such as B. a huge noise canceling headphone for your home?

Researchers in Singapore have developed a device that can be placed in a window to reduce incoming sound by 10 decibels. The system was developed by a team of scientists, including Masaharu Nishimura, who developed the basic concept, and Bhan Lam, a researcher at Nanyang Technological University in Singapore.

“I grew up in Singapore,” said Dr. Lam in a zoom interview from his apartment there. “It is a small town with a lot of noise, so I have a certain motivation to solve this problem.”

Their results were published in scientific reports on Thursday. The prototype is not yet the most practical device under real conditions, but it shows the way to develop technologies that can help reduce the burden of noisy city life.

Following the same technological principles as with noise canceling headphones, the team expanded the concept to an entire room by placing 24 small speakers in a window. The speakers emit sound waves that correspond to the incoming racket and neutralize it – or at least part of it.

The system is based on the frequency of the sound waves and the optimal range is currently between 300 and 1,000 Hertz.

In Singapore, a city near the equator, where temperatures are often high, overlapping traffic systems and the desire for natural ventilation in modern high-rise apartment towers can be a mystery to healthy living.

Dr. Lam said that “in places like Singapore, we want to keep the windows open as much as possible” to reduce the use of carbon intensive air conditioning and prevent the formation of stale air, which can pose health risks for some people.

But with the windows open, the constant noise of city traffic, trains, flying jets and construction machinery can rattle the apartments. The so-called anti-noise control window is the sonic equivalent of closing a window.

Every sound is the best way to reduce it, the source, like the silencer of a weapon. Therefore, the researchers treated the window opening itself as a source of noise, since most of the noise enters a room in this way.

The system uses a microphone outside the window to capture the repetitive sound waves from the interfering noise source, which are registered by a computer control. This in turn decodes the correct wave frequency required to neutralize the sound that is transmitted to the speakers inside the window frame.

The speakers then send out the right “anti” waves that pick up the incoming waves, and there you have it: almost blissful silence.

“When you sit in the room, you have the same feeling as when you press the noise canceling headphone switch,” said Dr. Lam and spread his hands to show the calming effect.

The system is best able to dampen the audible explosions from the types of stationary noise sources that are in the optimal frequency range.

Unfortunately, human voices don’t fit in most of this area. One of the next hurdles will be to find a way to silence loud conversations on the other side of the way.

Another limitation is that the system is unable to neutralize sporadic noises such as fireworks, car horns, or the occasional deafening impact of metal shop windows – the type of noise that causes many New Yorkers to slam their windows.

One reason for frequency limitation is the size of the speakers. Larger bass speakers would be required to compensate for lower frequencies. However, this would affect ventilation and your ability to see through the window.

It’s a compromise, and one solution might be to install larger windows or find a way to work with smaller speakers.

As it is, the 24 speakers, each about 2 inches in diameter, are an aesthetic obstacle.

“One complaint we get is that it’s ugly,” said Dr. Lam.

But if it can neutralize the sound of the jet taking off from Runway 13 in LaGuardia, that’s (quiet) music for the ears.


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