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...,-.„. <br /> 51. <br /> rA ' <br /> k. <br /> 41 put it another way, L dn is CNEL simplified . In cases where both <br /> descriptors have been used to describe the same set of operations , the <br /> results generally are the same or within 1 dB of eactli other. <br /> 0 <br /> 0 <br /> CNEL : SENEL + 10 log10 (Nd + 3Ne + 10 Nn) - 49j4 . <br /> t.. <br /> .T= <br /> N • * <br /> t! i <br /> f Figure 8 shows the approximate relationships between the cumulative <br /> k energy measures described here. No precise relationships can be made <br /> because of the variations in the way pure tones , duration. , and evening <br /> 1 <br /> and nighttime weightings are handled , but for the majority of airport <br /> environments over the range of levels that are of Concern , the <br /> :•• <br /> relationships are reasonable within a tolerance of plus or minus 3 dB. <br /> Table 4 summarizes the factors considered in each of the cumulative <br /> energy measures . <br /> • <br /> NEF I 11111111 III Iii I III <br /> 25 30 35 40 45 <br /> III <br /> 1 <br /> , <br /> , <br /> Leq(24) . <br /> 57 60 62 65 67 70 72 75 77 <br /> Ldna I 1 1 i 1 I i _j _j I j j 1 1 1 1 1 t i 1 II <br /> .• <br /> CNEL 60 65 70 75 80 <br /> FIG. 8. RELATIONSHIPS BETWEEN CUMULATIVE ENERGY MEASURES. <br /> I <br /> TABLE 4. SUMMARY OF FACTORS IN EACH CUMULATIVE ENERGY MEASURE, <br /> I <br /> --..,, Measure <br /> -..,..... <br /> ---.. <br /> —., <br /> Factor -...,....„ <br /> NET L eq L dn I CNEL <br /> Baste measure of Effective perc‘qvci Sound cx- :',713nt ,xpo:iur-r level Sinp,:. ,!,-cnt :;•rir,e exposure <br /> noise from single events noise level ensure le: l. ltv6: I <br /> I <br /> Annoyance due to 1 . <br /> Yes No :!0 1 Jc <br /> pure tones considered <br /> i <br /> Time periods considered Day (7 an -1.0 p,r1J Period must Elly 17 %,r; -1C r 7...) :g* :r EiLm,-7 p.r) i <br /> !(ight (10 p-n -7 n m ) bc npr!cif!■!-1 Ni,•h' ;1.1 : :; -- ■ rn.) Ew.r•01,-. i7 p n - 1-; p.m.) <br /> a.m. ) <br /> Weightings applied to Day 0 in 0 15 re : !- any C ti (-my k dE <br /> events in each period Night 17 J lens or :;1'ht 0 AP Ev,n - 15 dr, <br /> 410 <br /> perk! !ii,;ht n de. <br /> 21 <br /> .. 1 <br /> 1 ,s1,,r,„. ...:,.4+44.;m VE7',/iI! .1'. ;.: ;.- . <br />