Pt. 36, App. A
14 CFR Ch. I (1-1-18 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,
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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,