7
UNIT
5ft
MICROPHONE
CEILING
4-2. NOISE CRITERION CURVES
90
80
70
60
50
40
30
20
10
63
125
250
500
1000
2000
4000
8000
APPROXIMATE
THRESHOLD OF
HEARING FOR
CONTINUOUS
NOISE
NC-60
NC-50
NC-40
NC-30
NC-20
NC-70
OCT
A
VE BAND SOUND PRESSURE LEVEL, dB (0 dB = 0.0002
μ
bar)
BAND CENTER FREQUENCIES, Hz
High
Medium
39
SPL(dB)
34
LINE
NOTCH
Low
30
PLFY-P12NCMU-E.TH
PLFY-P12NCMU-E
1
.TH
PLFY-P12NCMU-ER2.TH
90
80
70
60
50
40
30
20
10
63
125
250
500
1000
2000
4000
8000
APPROXIMATE
THRESHOLD OF
HEARING FOR
CONTINUOUS
NOISE
NC-60
NC-50
NC-40
NC-30
NC-20
NC-70
OCT
A
VE BAND SOUND PRESSURE LEVEL, dB (0 dB = 0.0002
μ
bar)
BAND CENTER FREQUENCIES, Hz
High
Medium
40
SPL(dB)
35
LINE
NOTCH
Low
31
PLFY-P15NCMU-E.TH
PLFY-P15NCMU-E
1
.TH
PLFY-P15NCMU-ER2.TH
90
80
70
60
50
40
30
20
10
63
125
250
500
1000
2000
4000
8000
APPROXIMATE
THRESHOLD OF
HEARING FOR
CONTINUOUS
NOISE
NC-60
NC-50
NC-40
NC-30
NC-20
NC-70
OCT
A
VE BAND SOUND PRESSURE LEVEL, dB (0 dB = 0.0002
μ
bar)
BAND CENTER FREQUENCIES, Hz
PLFY-P08NCMU-E.TH
PLFY-P08NCMU-E
1
.TH
PLFY-P08NCMU-ER2.TH
High
Medium
38
SPL(dB)
32
LINE
NOTCH
Low
29
NOTE: The sound level is measured in an anechoic
room where echoes are few, when compres-
sor stops. The sound may be bigger than the
indicated level in actual use due to surround-
ing echoes. The sound level can be higher by
about 2 dB than the indicated level during cool-
ing and heating operation.
