Pt. 36, App. A Symbol Unit Meaning Symbol Unit Meaning SPL- (i, k) .... dB re ........... 20 SectionPa hr ................. q ................... Degrees ....... Degrees ....... SPL(i) ........... dB re ........... 20 SectionPa Adjusted sound pressure level. The first approximation to background sound pressure level in the i-th one-third octave band for the k-th instant of time. Maximum sound pressure level. The sound pressure level that occurs in the i-th one-third octave band of the spectrum for PNLTM. Corrected maximum sound pressure level. The sound pressure level that occurs in the i-th one-third octave band of the spectrum for PNLTM corrected for atmospheric sound absorption. Final background sound pressure level. The second and final approximation to background sound pressure level in the i-th one-third octave band for the k-th instant of time. Elapsed time. The length of time measured from a reference zero. Time limit. The beginning and end, respectively, of the noise time history defined by h. Time increment. The equal increments of time for which PNL(k) and PNLT(k) are calculated. Normalizing time constant. The length of time used as a reference in the integration method for computing duration corrections, where T = 10s. Temperature. The ambient air temperature. Test atmospheric absorption. The atmospheric attenuation of sound that occurs in the i-th one-third octave band at the measured air temperature and relative humidity. Reference atmospheric absorption. The atmospheric attenuation of sound that occurs in the i-th one-third octave band at a reference air temperature and relative humidity. First constant climb angle (Gear up, speed of at least V2 + 10 kt (V2 + 19 km/h), takeoff thrust). Second constant climb angle (Gear up, speed of at least V2 + 10 kt (V2 + 19 km/h), after cut-back). Thrust cutback angles. The angles defining the points on the takeoff flight path at which thrust reduction is started and ended respectively. Approach angle. y .................. Degrees ....... Section .................. ..................... Reference approach angle. Noise angle (relative to flight path). The angle between the flight path and noise path. It is identical for both measured and corrected flight paths. Noise angle (relative to ground). The angle between the noise path and the ground. It is identical for both measured and corrected flight paths. Engine noise emission parameter. Reference engine noise emission parameter. PNLT correction. The correction to be added to the EPNL calculated from measured data to account for noise level changes due to differences in atmospheric absorption and noise path length between reference and test conditions. Adjustment to duration correction. The adjustment to be made to the EPNL calculated from measured data to account for noise level changes due to the noise duration between reference and test conditions. Source noise adjustment. The adjustment to be made to the EPNL calculated from measured data to account for noise level changes due to differences between reference and test engine operating conditions. SPL- (i, k) .... dB re ........... 20 SectionPa t .................... s .................. t(1), t(2) ........ s .................. Dt ................. s .................. T .................. s .................. t(SectionF) (SectionC) ...... SectionF, SectionC .......... a(i) ............... dB/1000ft db/ 100m. a(i)o .............. dB/1000ft db/ 100m. A1 ................. Degrees ....... A2 ................. d ................... e h .................. Degrees ....... Degrees ....... Degrees ....... Sectionr .................. ..................... D1 ................. EPNdB ........ D2 ................. EPNdB ........ D3 ................. EPNdB ........ Section A36.7 Sound Attenuation in Air A36.7.1 The atmospheric attenuation of sound must be determined in accordance with the procedure presented in section A36.7.2. A36.7.2 The relationship between sound attenuation, frequency, temperature, and humidity is expressed by the following equations. A36.7.2(a) For calculations using the English System of Units: (i) = 10 [2.05log ( f + ( ) 10 ) 0 /1000 + 6.33 10 - 4 [log ( f ) + 4.6833 10 0 - 3 12:50 Apr 30, 2019 Jkt 247046 PO 00000 Frm 00804 Fmt 8010 ] - 2. 4215 ] and = 1010 ( log H - 1.97274664 + 2.288074 10 - 2 ) 10 f (0) 10 ( - 9.589 10 - 5 2 + 3.0 10 - 7 3 ) 794 VerDate Sep<11>2014 - 1. 45325 Sfmt 8006 Y:\SGML\247046.XXX 247046 ER08JY02.011 dB re ........... 20 SectionPa ER08JY02.010 SPL(i)r .......... spaschal on DSK3GDR082PROD with CFR 14 CFR Ch. I (1-1-19 Edition)