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
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- 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
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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)