A new device may bring fresh air to people who live or work in city buildings -- without letting in the noise from traffic. Developed by Chris Field, senior acoustic consultant at the Sydney, Australia, offices of engineering firm Arup, and Fergus Fricke, honorary associate professor at the University of Sydney, the polycarbonate brick has a channel cut through it that allows air to flow through. To stop street noise from doing the same, small tubular cavities lead off the channel. The air flowing over the mouths of the cavities causes them to resonate, creating small differences in pressure that scatter the sound waves, dissipating most of the traffic noise before it reaches the end of the channel. Field and Fricke claim the device cuts inbound noise by 85 percent, and they've licensed the technology to Silenceair in New South Wales, Australia.