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within *1.0 dB with respect to the input signal, after all systematic
errors have been eliminated. The total systematic errors for
each of the output levels shall not exceed *3 dB. For contiguous
filter systems, the systematic correction between adjacent
one-third octave channels shall not exceed 4 dB.
3.4.8 The dynamic range capability of the analyser for
display of a single aeroplane noise event shall be at Least
3.5.1 The microphones shall be oriented in a known
direction so that the maximum sound received arrives as
nearly as reasonable in the direction for which the microphones
are calibrated. The microphones shall be placed so that
their sensing elements are approximately 1.2 m (4 ft) above
ground.
3.5.2 Immediately prior to and after each test, a recorded
acoustic calibration of the system shall be made in the field
with an acoustic calibrator for the two purposes of checking
system sensitivity and providing an acoustic reference level for
the analysis of the sound level data.
3.5.3 For the purpose of minimizing equipment or operator
error, field calibrations shall be supplemented whenever practicable
with the use of an insert voltage device to place a known
signal at the input of the microphone, just prior to and after
recording aeroplane noise data.
3.5.4 Background noise, including ambient noise and
electrical noise of the measurement systems, shall be recorded
and determined in the test area with the system gain set at
levels which will be used for aeroplane noise measurements. If
aeroplane sound pressure levels do not exceed background
sound pressure levels by at least 10 dB in any significant
one-third octave band, approved corrections for the contribution
of background sound pressure level to the observed
sound pressure lcvcl shall be applicd.
4. CALCULATION OF EFFECTIVE
PERCEIVED NOISE LEVEL FROM
MEASURED NOISE DATA
4.1 General
4.1.1 Thc basic clcment in thc noisc certification
criteria shall be the noise evaluation measure designated
effective perceived noise level, EPNL, in units of EPNdB,
which is a single number evaluator of the subjective effects
of aeroplane noise on human beings. Simply stated, EPNL
24/11/05 APP 1-4
Table Al-1. Noys as a function of sound pressure level (29dPL<89)
Onelhird octave bend antre fmquendes (Hz)
315 400 YX) 630 8W 1OW 1250 1600 2WO 2YX)
SPL
-(dB)
29
30
31
32
33
34
35
38
37
38
39
SPL
(dB) -
90
91
92
93
94
95
96
97
98
99
100
101
1 02
103
104
955 1098
NOV. 1967
Table
-
160
-
22.6
24.3
26 0
27.9
29.9
32.0
34 3
36 8
39.4
42.2
45 3
46.5
52.0
55.7
59.7
54.0
68.6
735
78.8
84.4
90.5
97.0
104
111
119
128
137
147
158
169
181
194
208
223
239
256
274
294
31 5
338
382
388
41 6
446
476
51 2
549
588
830
676
724
776
832
691
95 5
1024
1098
1176
1261
1351
1446 -
At-1 (cont.). Noys as a function of sound pressure level (9(kSPL<150)
One-third octave band
200 250 315 400 500 630
I centre frequencms (Hz)
800 1 m 1250
Appendix I Annex 16 - Environmental Protection
shall consist of instantaneous perceived noise level, PNL,
corrected for spectral irregularities (the correction, called
"tone correction factor", is made for the maximum tone only
at each increment of time) and for duration.
4.1.2 Three basic physical properties of sound pressure
shall be measured: level, frequency distribution, and time variation.
More specifically, the instantaneous sound pressure
level in each of 24 one-third octave bands of the noise shall be
required for each one-half second increment of time during the
aeroplane flyover.
4.1.3 The calculation procedure which utilizes physical
measurements of noise to derive the EPNL evaluation measure
of subjective response shall consist of the following five steps:
a) the 24 one-third octave bands of sound pressure level
are converted to perceived noisiness by means of a noy
table.6 The noy values are combined and then converted
to instantaneous perceived noise levels, PNL(k);
b) a tone correction factor, C(k), is calculated for each
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