22
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
BAND CENTER FREQUENCIES, Hz
OCTAVE BAND SOUND PRESSURE LEVEL, dB
(0 dB = 0.0002 µbar)
Hi
NOTCH
Lo
41
SPL(dB)
33
LINE
PLH-4AKS.UK
PLH-4AKS
1.UK
PLH-4AKHS.UK
PLH-4AKHS
1.UK
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
OCTAVE BAND SOUND PRESSURE LEVEL, dB
(0 dB = 0.0002 µbar)
BAND CENTER FREQUENCIES, Hz
PLH-3AK.UK
PLH-3AK
1.UK
PLH-3AKH.UK
PLH-3AKH
1.UK
Hi
Lo
34
SPL(dB)
28
LINE
NOTCH
6. 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
BAND CENTER FREQUENCIES, Hz
OCTAVE BAND SOUND PRESSURE LEVEL, dB
(0 dB = 0.0002 µbar)
Hi
NOTCH
Lo
45
SPL(dB)
37
LINE
PLH-6AKS.UK
PLH-6AKS
1.UK
PLH-6AKHS.UK
PLH-6AKHS
1.UK
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
BAND CENTER FREQUENCIES, Hz
OCTAVE BAND SOUND PRESSURE LEVEL, dB
(0 dB = 0.0002 µbar)
Hi
NOTCH
Lo
43
SPL(dB)
35
LINE
PLH-5AKS.UK
PLH-5AKS
1.UK
PLH-5AKHS.UK
PLH-5AKHS
1.UK
OC211-A--1.qxp 04.9.28 4:39 PM Page 22