A Waterfall in Brooklyn (part 1 of 2)

04.15.2009 | HMMH |

by Doug Barrett

Being a noise geek has its pluses and minuses.  On the upside, entertainment, or at least distraction, due to acoustical phenomena seldom is far away.  Whether it’s my fascination with the reflected “phipp…phipp…phipp” heard while driving windows-down past a row of utility poles or the tonal qualities of different pavement types, my fabulous spouse has long tolerated this quirk.  Every now and then however, we come across a “noise moment” that even she admits is really cool.

A few weeks ago, while in Albany, New York, attending a college hockey tournament, we took a late-afternoon stroll around the Empire State Plaza just prior to the finals.  This 98-acre government plaza, conceived by Governor Nelson Rockefeller to be “the most electrifying capital in the world,” was constructed between 1965 and 1978.  One of the Plaza’s more attention-grabbing features is the futuristic performance venue known as “the Egg.”  Like something from the Jetsons, this unique, cantilevered structure appears to hover overhead, but in reality is anchored by a central core that descends underground six stories.

At one point we stood at the edge of the Plaza looking down on a roadway passing below.  As we turned and walked away from the parapet, the traffic noise from below first decreased (due to the parapet acting as a noise barrier), but then increased again in volume.  Oddly, the traffic noise seemed to come not from the roadway, but from above us near the center of the Plaza.  Both of us were fascinated by the clarity of the auditory “image” that we heard as each individual vehicle passed from one side to the other – just as if we were standing by the side of the road as the vehicles zipped by!

Traffic noise reflecting off the Egg’s underbelly produced this surprising effect.  By blocking the direct sound-propagation path from the roadway, the 40-foot high retaining wall acted as a noise barrier.  At the same time, like a giant inside-out parabolic mirror, the smooth, convex Egg reflected traffic noise to the plaza below as the virtual image of each vehicle traced its way across the Egg’s surface.

After taking this in, we had to hustle to make it to the hockey game on time, and all thoughts of acoustical phenomena were lost to the action on the ice.  Well, mostly.  Did you ever notice how the “clank” of a hockey puck striking the goal post is audible even in an arena with thousands of screaming spectators?  But later, after the disappointment of “my” team’s loss began to wear off, I reflected some more on what we had heard beneath the Egg, and another historic New York State public works project came to mind (to be continued).