Pt. 36, App. A 14 CFR Ch. I (1-1-19 Edition) A36.9.3.2.1 The one-third octave band levels SPL(i) comprising PNL (the PNL at the moment of PNLTM observed at K) must be adjusted to reference levels SPL(i)r as follows: A36.9.3.2.1(a) For calculations using the English System of Units: In this expression, (1) The term 0.001[a(i)Sectiona(i)0]QK is the adjustment for the effect of the change in sound attenuation coefficient, and a(i) and a(i)0 are the coefficients for the test and reference atmospheric conditions respectively, 800 VerDate Sep<11>2014 12:50 Apr 30, 2019 Jkt 247046 PO 00000 Frm 00810 Fmt 8010 Sfmt 8003 Y:\SGML\247046.XXX 247046 ER08JY02.017 spaschal on DSK3GDR082PROD with CFR SPL(i)r = SPL(i) + 0.001[a(i)Sectiona(i)0]QK + 0.001a(i)0(QKSectionQrKr) + 20log(QK/QrKr) determined under section A36.7 of this appendix; (2) The term 0.001a(i)0(QK Section QrKr) is the adjustment for the effect of the change in the noise path length on the sound attenuation; (3) The term 20 log(QK/QrKr) is the adjustment for the effect of the change in the noise path length due to the - inverse square - law; (4) QK and QrKr are measured in feet and a(i) and a(i)0 are expressed in dB/1000 ft. A36.9.3.2.1(b) For calculations using the International System of Units: SPL(i)r = SPL(i) + 0.01[a(i)Sectiona(i)0]QK + 0.01a(i)0 (QK Section QrKr) + 20 log(QK/QrKr) In this expression,