As residential construction moves closer to urban rail

As residential construction moves closer to urban rail lines, bridges, and freeway ramps, developers are increasingly using sound-muffling windows and other techniques to keep noise out of new housing. A window wall for a 60-story condo tower next to a San Francisco bus terminal will have two panes, one slightly thicker than the conventional quarter-inch, with a half-inch between them to block the sound of buses, The New York Times reported in a Feb. 17 article about noise remedies. At Beacon Towers, next to the Manhattan Bridge in Brooklyn, developer Leviev Boymelgreen lets buyers inspect a sample window consisting of two half-inch-thick panes with eight inches of air in between. To emphasize the potential for “Zenlike calm,” the Beacon Towers sales office encourages buyers to put on headsets and listen to the difference between the noise level with standard windows and with custom windows. Denis R. Milsom of acoustics consultants Shen Milsom & Wilke said the special windows reduce the noise level from 96 decibels outside to 40 inside. The New York zoning code allows 45 decibels on the interior. The sound-muffling windows reportedly cost about twice as conventional windows. San Francisco acoustical engineer Charles Salter, noting that his firm handles about four times as many residential projects with sound problems as five years ago, regularly recommends laminated glass and extra layers of gypsum board. In projects where noise will prevent residents from opening their windows to get fresh air, San Francisco architect Glenn Rescalvo has specified special vents, which bring air in through window mullions that contain tiny holes.