10
OCHT669
NOISE CRITERION CURVES
UNIT
4 ft
MICROPHONE
CEILING
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
AVE BAND SOUND PRESSURE LEVEL, dB (0 dB = 0.0002 µbar)
BAND CENTER FREQUENCIES, Hz
High
Medium
31
SPL(dB)
28
LINE
<60Hz>
NOTCH
Low
25
NTXCKS09A112AA
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
AVE BAND SOUND PRESSURE LEVEL, dB (0 dB = 0.0002 µbar)
BAND CENTER FREQUENCIES, Hz
High
Medium
39
SPL(dB)
34
LINE
<60Hz>
NOTCH
Low
27
NTXCKS15A112AA
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
AVE BAND SOUND PRESSURE LEVEL, dB (0 dB = 0.0002 µbar)
BAND CENTER FREQUENCIES, Hz
High
Medium
34
SPL(dB)
30
LINE
<60Hz>
NOTCH
Low
25
NTXCKS12A112AA
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
AVE BAND SOUND PRESSURE LEVEL, dB (0 dB = 0.0002 µbar)
BAND CENTER FREQUENCIES, Hz
High
Medium
43
SPL(dB)
40
LINE
<60Hz>
NOTCH
Low
32
NTXCKS18A112AA
NOTE: The sound level is measured in an anechoic room where
echoes are few, when compressor stops. The sound
may be bigger than the indicated level in actual use due
to surrounding echoes. The sound level can be higher
by about 2 dB than the indicated level during cooling
and heating operation.
