Handbook for Sound Engineers

68 Chapter 4

musicals, and plays are low to assure maximum
dynamic range for music and greatest intelligibility for
speech. This same reasoning applies to high-quality

listening rooms such as control rooms. For recording

studios, stringent NC goals are required to minimize

noise pickup by the microphone. Levels below NC-30

are generally considered “quiet,” but there are different

degrees of quietness. An NC-25 is at the low end of

what is expected of an urban residence. This means that

Figure 4-2. PNC. From Gold Line TEF20. Note extra octave.

Figure 4-3. NR—The European noise rating curves. From Gold Line TEF 20. Note the extended range.

32 64 125 250 500 1000 2000 4000 8000

Frequency—Hz

90

80

70

60

50

40

30

20

10

Re = 2 × 10

5 Pascals

65

60

55

50

45

40

35

30

25

20

15

32 64 125 250 500 1000 2000 4000 8000

Frequency—Hz

Re = 2 × 10

5 Pascals

(^10095)
(^9085)
(^8075)
(^7065)
(^6055)
(^5045)
(^4035)
(^3025)
(^2015)
(^105)
0
100
90
80
70
60
50
40
30
20
10
0

10
Figure 4-4. Balanced noise-criterion (NCB) curves for occu-
pied room.
Table 4-2. Noise Criteria Ranges, NC and NCB
Use of Space Noise Criteria Range NCB
Private urban residence, corri-
dors
25 – 35 25 – 40
Private rural residence 20 – 30 na
Hotel rooms 30 – 40 25 – 40
Hospital, private rooms 25 – 35 25 – 40
Hospital, lobby, corridors 35 – 45 40 – 50
Office, executive 30 – 40 30 – 40
Offices, open 35 – 45 35 – 45
Restaurant 35 – 45 35 – 45
Church sanctuary 20 – 30 20 – 30
Concert, opera halls 15 – 25 10 – 15
Studios, recording and sound
reproduction
15 – 25 10
Selected from references 2, 3, and 5