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From page 22...
... 4 Detailed Analyses: Overall Description This section describes the methods used to analyze the measured and modeled SEL values of the aircraft types identified in the previous section. Generally, the analyses focus on the sound levels of the GA jet aircraft operating at the six airports of Table 3.
From page 23...
... Table 4 Aircraft types evaluated and numbers of useful associated flight track / SEL data points Order Designator Description INM Aircraft Type Used Number Data Points Arrival Departure 1 H25B* British Aerospace BAe-125-700/800; Hawker 750, 800, 800XP, 900XP LEAR35*
From page 24...
... general area where DNL 65 dB is likely to occur.16 By determining average track distances to DNL 65 dB for the study airports, 12,000 feet from the takeoff end (assumed location of brake-release) of the runway for departures and 9,000 feet from landing threshold for arrivals were selected.17 4.2.1 Sound Exposure Level Discrepancies The SEL discrepancy for an aircraft type is the difference between the energy average measured SEL and the energy average modeled SEL.18 The energy average SEL is the basic metric used to compute DNL, rather than the arithmetic average SEL.
From page 25...
... needed an additional increase in level of approximately +2.7 dB.20 Once all SEL values for a given aircraft type were adjusted, then the net effect on the energy average modeled SEL was determined. Measured minus modeled sound exposure levels, the decibel effect of altitude discrepancies, and discrepancies that result if the altitude could be corrected are presented in Section 5.

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