25
90
80
70
60
50
40
30
20
10
63
125
250
500
1000
2000
4000
8000
APPROXIMATE
TERESHOLD 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 re 0.0002 MICRO BAR
BAND CENTER FREQUENCIES, Hz
PKA-RP1.6GAL
PKA-RP2GAL
Hi
NOTCH
Mi1
Mi2
Lo
43
SPL(dB)
41
38
36
LINE
5-6. NOISE CRITERION CURVES
UNIT
WALL
1m
1m
MICROPHONE
OC305--1.qxp 04.4.28 11:24 AM Page 25
