Page 15 - Winter 2009

Fig. 7. Maximum A-level noise zones for six random nights with northerly takeoff flow (10:30 p.m. to 6:00 a.m.). Black, green, red, and blues indicates levels greater than 70, 75, 80, and 85 dB, respectively.
Fig. 8. Maximum A-level noise zones for three random nights with southerly takeoff flow (10:30 p.m. to 6:00 a.m.). Black, green, red, and blues indicates levels greater than 70, 75, 80, and 85 dB, respectively.
14 Acoustics Today, October 2009
Results
The results after the trial and several months of negotiations urged by the court was a negotiated settlement of 128 million dollars to insulate homes in the DNL 60–65 dB zone as established by MSP in the City of Minneapolis and the suburbs of Eagan and Richfield. This is believed to be by far the largest noise settlement ever estab- lished. Several conclusions can be drawn from this study—(1) urban communities can be very quiet, absent a single noisy source such as an airport; (2) most airport noise monitors overstate the true com- munity noise, sometimes by large amounts; (3) by itself, an indoor level of 45 dB is not a valid criteri- on; rather, outdoors less than 55 dB and indoors less than 45 dB are the proper pair of criteria; and (4) One can calculate the probability of being awakened at least once by a whole night’s set of events.AT
References
1 ANSI S12.9 Part 6, American National Standard Quantities and Procedures for Description and Measurement of Environmental Sound—Part 6: Methods for Estimation of Awakenings. (American National Standards Institute, New York).
2 EPA. Information on Levels of Environmental Noise Requisite to Protect Public Health and Welfare with an Adequate Margin of Safety,
US Environmental Protection Agency, Office of Noise Abatement and Control (ONAC), Report EPA550/9-74-004, Washington D.C.
3 Federal Interagency Committee on Noise (FICON) Federal Agency Review of Selected Airport Noise Analysis, August 1992. www.fican. org/pdf/nai-8-92.pdf. (Last viewed 11/19/2009).
4 Sanford Fidell and Laura Silvati, “Parsimonious alternative to regres- sion analysis for characterizing prevalence rates of aircraft noise annoyance,” Noise Control Eng. J. 52(2), 56-68 (March-April 2004).