“You must consider the soundscape in which this memorial will be witnessed,” implores Arline Bronzaft, a consultant and professor at City University of New York who has written extensively on the psychological impact of noise. “That’s a very noisy place. It’s one thing to have a visual memorial. Architects focus on visual. But to use the word ‘reflection’ means there should be some quiet in the surrounding so you could properly reflect.” Cemeteries and shrines, she points out, are sacred places, associated with solitude and silence. But Lower Manhattan, thrumming constantly with congestion and construction, is anathema to both. “Quiet is what we want for this experience–unless they want people to remember the thundering outbursts of that day. I don’t think so.”
Bronzaft’s concerns are actually twofold: one is that the surrounding environment may intrude upon visitors paying quiet homage. The other is that the waterfall itself–which may turn out to be the largest built by human hands–will generate an obnoxious crashing cacophony. Her anxiety is also shared by others. Lower Manhattan, especially with all its construction since 2001, is “too loud,” says City Councilman Alan Gerson. “Noise remains one of the major complaints that governmental offices receive about conditions downtown, and it comes from a variety of sources ranging from noisy party boats that operate out of some of our marinas, to construction going on at hours when it should not, to traffic in parts of the area where we have noisy clubs. And we know that the site has the potential to make the situation much worse, whether it’s from excessive traffic or noise from the site itself.”
How loud is too loud? It’s a question that divides experts, but many agree exposure to noises louder than 85 decibels over time will lead to a loss in hearing, according to the League for the Hard of Hearing. Steady, heavy traffic produces 85 decibels of sound. So does a handsaw, a loud vacuum cleaner or a trendy restaurant. (Rainfall registers about 50 decibels, normal conversation around 60.) New Yorkers are a rowdy lot; Lower Manhattan, in its natural state, probably is, to borrow the councilman’s words, “too loud.” But Peter Walker, the landscaper who codesigned “Reflecting Absence,” says street-level sound does not keep him up at night. “If you think about it, the fact that there are so many people, they’re all in those buildings. It’s the people on the street, and the street’s of a certain size. That doesn’t worry me.”
The Lower Manhattan Development Corporation’s Web site describes a memorial consisting of two chasms where the Twin Towers once stood. Water falls 30 feet from ground level into a pool where it then drains off another 15-foot ledge. “Descending into the memorial, visitors are removed from the sights and sounds of the city and immersed in a cool darkness,” the description reads. “As they proceed, the sound of water falling grows louder, and more daylight filters in from below.” One goal, then, is to drown out the honking urban din with a gentle roar of water.
The engineering challenges presented by the design itself have been well documented: Walker and Arad have to figure out how to keep water from splashing visitors and freezing in winter, for example, and the size of the waterfalls may have to be scaled smaller than the tower footprints to accommodate the jangle of subways and service roads and other underground infrastructure. And just how loud will the 45-foot waterfalls have to be to drown out Lower Manhattan’s clamor? Will the bedrock level itself become just one massive echo chamber? Even Walker concedes he doesn’t know. “I think we both are now looking at trying to get the amount of water down as low as we can. The sound isn’t really coming from the amount of water, it’s coming from when it hits. I’ve done a number of things where you have a long line of water falling. And I’ve also done some waterfalls where you get behind them. The sound generally is like a white sound, it’s enough to cover the normal roar of the street, except sirens. Then the question is: how much more sound will there be? There’s at least 800 feet of this stuff and that’s one hell of a lot of water.”
No doubt, the sound of falling water is a different type of noise than traffic or overhead aircraft, even at the same decibel level. It even has a positive connotation for most people. William J. Cavanaugh, coeditor of the 1998 book “Architectural Acoustics: Principles and Practice,” points out that “people say they go to the quiet solitude of the forest. But you get to most forests, especially if they have any waterfalls, you find it gets pretty damn noisy. Yet people still would stay.” To extend that point to “Reflecting Absence,” Cavanaugh remembers his first visit to the Franklin Delano Roosevelt Memorial on the National Mall in Washington: the fountains at the site masked the sounds of passing airplanes that had bothered him so much at the Vietnam Memorial just a few hundred yards away. The planes were still overhead–as loud and irritating as ever–but the fountains were even louder, yet they imbued the scene with serenity. Cavanaugh calls it “‘acoustical perfume,’ where you use one sound to mask or cover up another kind of annoying sound.” But, he warns, at a certain point even acoustical perfume can get too loud. “It’s like all good things. Even with perfume, you’ve got to take a bath once in a while.”
