Acoustical Engineer Testifies Before Zoning Board

Acoustical Engineer Mary Eagen of Harris, Miller, Miller, and Hanson testified before the zoning board on Monday night as part of the ongoing hearing of Overlook Hospital's application for a height variance to construct a helistop on the roof.

Eagen recapped her testimony from last month by saying her analysis of the sound measurements her firm took in the field and the projections they did for other sites around the city show the noise produced from a helistop would be consistent with current existing city noise ordiances.

However there was some discussion as to whether the formula used to measure the noise and to project sound experiences was consistent with the state and city standards.

Eagen was asked last month to create a new exhibit that would show the sound contours of a night flyover. Eagen said after looking at hospital records over the last two years, 18 percent of 116 flights occured at night. Night is defined by the Federal Aviation Administration at 10 p.m. to 7 a.m.

The new exhibit showed average sound contours for a 24 hour period but took into consideration that 18 percent of flights could occur at night. Eagen said the model shows the 65 decible contour is contained to the roof of Overlook Hospital and the 60 contour level is contained to this hospital's property.

Eagen and her firm took physical measurements during a test flyover to validate the projections their model came up with.

Eagen reported that measuresments for individual sound events could result in speech interference and sleep awakening.

The three sites for actual field measurements were 17 Glenside Avenue, 146 Morris Avenue or the Italian-American Club, and 86 Morris Avenue or the Celegene Corporation.

"The sites were identified because of their proximity to the approach flight patch," Eagen said.

Eagen also chose several other "noise sensitive sites" to compute continuous noise levels for. The values ranged from less then 55 decibels at the Glenside Avenue location to less than 45 decibels at a location on Oak Ridge Avenue.

"At all of the residential areas the values we computed were below the standard," she said.

However, Eagen explained the algorithm used is "unfiltered" meaning it assumes there are no structures, topography or vegetation between the noise source and the site of the measurement or computation. Things such as buildings and trees can reflect or defract sound waves.

Eagen reported that at 17 Glenside Avenue there would be 25 seconds of indoor speech interference on both arrival and departure. She also said that out of 50 landings and 50 departures, an individual at Glenside Avenue would have a 5 percent chance of sleep awakening at that noise level.

At site 2, the Italian-American Club, the noise level would be more than 65 decibles for 30 to 70 seconds and 146 Morris Ave. the maximum noise level was just below 80 decibles.

In order to take additional calculations and for board members and the public to experience the noise firsthand, there will be two flyovers Saturday. The first at Morristown Memorial will be an actual landing at the hospital's existing helipad at 10 a.m. The helicopter will then flyover Overlook at 11:30 a.m.