The Art and Science of Peace and Quiet

Architects and engineers follow a variety of high and low paths in an effort to keep external noise out of buildings and improve desired sound within.
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From Architectural Record
Sara Hart

"Windows are the weakest link with regard to noise control," says SM&W partner Denis Milsom. "With subways, the rumble noise is the most difficult to deal with. It's a low-frequency noise, and it goes through the windows." Research shows that low-frequency noises disturb people the most. In the case of the Brooklyn building, 85 Adams Street, such problems were anticipated by heavy bridge and rail traffic, so blocking infiltration into the apartments was, predictably, a priority for the developer. The engineer's solution, therefore, was resolved in the glazing and wall system. The window unit consists of 1¼2-inch laminated glass on the exterior face and a 1¼2-inch pane on the interior, separated by an airspace of 8 inches, resulting in a wall assembly that's a remarkable 10 inches thick. (The acoustic windows were developed by specialty contractor St. Cloud Windows of Minnesota.)


The Mandarin Oriental Hotel in Washington, D.C. (above), is located on an "acoustically challenged" site (below).

Photography: Courtesy BBG/BBGM

This airspace is quite deep for nonindustrial buildings. Conventional acoustical wisdom warns that a wide air cavity can create convection within the space, increasing heat loss. Christopher Pollack, SM&W project manager, insists, "The cavity we created was sufficient to meet all the codes required. The acoustical construction consists of very heavy laminated glass, which may actually increase thermal performance." He further explains, "The frame for this window is in two parts, an outside frame and an inside frame. These are joined by rubber to help break sound from transmitting from one side to another. This acoustical break will also help in reducing the transmission of heat."

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Airspace prevents what is called "coincidence decoupling," where the two lites of glass in an insulated window vibrate together at a certain frequency. This tandem movement reduces the amount of sound that can be blocked at that frequency of vibration. Using a heavy glass and a large airspace between the glass usually eliminates this problem, which is not an issue in this case due to the depth of the windows.

An additional challenge was presented by the zoning code requiring natural ventilation. To accommodate this requirement, the window assembly has a trickle vent-an adjustable opening to provide controllable background ventilation. The vent conducts air along a lined path so as not also to transmit noise. SM&W recommended installing STC (sound transmission class) 56 windows on floors three through nine on the east and south facades. The developer, however, chose an even more conservative route and used them throughout the building at every floor.


The Southern California Institute of Architecture (SCI-Arc) in Los Angeles commissioned Hodgetts + Fung Design and Architecture to improve the acoustic quality of the school's main space (above). With the clever use of modest, low-tech materials-including aluminum tubes, nylon thread, and industrial-weight wool felt-the architects transformed the space visually as well as acoustically (below).

Photography: Courtesy Hodgetts + Fung

The overall construction consists of pre-engineered brick-and-metal panels mounted on a stud system. For the walls to conform to the engineer's noise-reduction criteria, two layers of gypsum wall board were required on both sides of the exterior walls, with additional insulation in the cavity (see wall section, page 144).

The noise problem is not specific to New York, of course. The Mandarin Oriental Hotel in Washington, D.C., designed by BBG-BBGM Architects, also working with SM&W, was built on the last piece of available real estate in Southwest Washington. The aerial panorama (page 145) suggests an ideal location with views across the Tidal Basin to the Jefferson Memorial and easy access to the Mall and Capitol. However, from this perspective, the eye can easily edit out the nearby freight-train line, which also carries commuter trains, and the major freeway that borders the site. It also doesn't reveal the fact that the site is on the flight path of Ronald Reagan National Airport, as well as a heavily traveled helicopter route.

 

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Originally published in Architectural Record.
Originally published in February 2005

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