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Noise Criterion (NC) Curves

Many on-orbit noise emission requirements make use of noise criteria (NC) curves as noise emission limits for individual components, payloads, and racks. NC curves are well-known standard criteria that are used in building acoustics to describe background noise associated with mechanical equipment and other self-noise sources found in unoccupied spaces. Tabulated values of standard NC curves are shown here for reference only. Please refer to the applicable requirements documents for specific limits and rules for their application.


Octave band values of Noise Criterion (NC) Curves


NC Curve
Octive Band Sound Pressure Level(dB)
63Hz
125Hz
250Hz
500Hz
1000Hz
2000Hz
4000Hz
8000Hz
NC 15
47
36
29
22
17
14
12
11
NC 20
51
40
33
26
22
19
17
16
NC 25
54
44
37
31
27
24
22
21
NC 30
57
48
41
35
31
29
28
27
NC 35
60
52
45
40
36
34
33
32
NC 40
64
56
50
45
41
39
38
37
NC 45
67
60
54
49
46
44
43
42
NC 50
71
64
58
54
51
49
48
47
NC 55
74
67
62
58
56
54
53
52
NC 60
77
71
67
63
61
59
58
57
NC 65
80
75
71
68
66
64
63
62

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Editor: Paul J. Passe
NASA Official: Beth A. Cooper
Last Updated: April 17, 2006