This is Scientific American's 60-second Science, I'm Christopher Intagliata.Restaurants, schools, dentist offices are all keeping more windows open to increase ventilation―and, hopefully, to decrease the chances of encountering the coronavirus.But letting in fresh air also lets in more noise.Now researchers have come up with a device that's like noise-cancelling headphones―but for a building."It works on the same principle, so it detects noise that's coming into the windows and then is cancelling the noise."Bhan Lam, an acoustical engineer at Nanyang Technological University in Singapore.The device looks like a grid of small speakers and fits over an open window.A microphone samples incoming noise, then sends the speaker grid instructions on what sort of "antinoise" to emit.The result is to cancel out the incoming sound.For example, here's the sound of a commuter train in Singapore with no noise control.Now here's that same sound with the array of noise-cancelling speakers turned on.Compare that to a closed window.The antinoise device is almost as good and allows air to keep flowing into and out of the window.The details are in the journal Scientific Reports.The device is just a prototype―so it's still expensive. And it doesn't block out all sounds.It only masks sound at frequencies from 300 to 1000 Hz―which includes the rumble of freeways, trains and planes.
