Mitsubishi Electric PKA-A12HA, Service Manual, Page: 8 / 36

8
5
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 (0dB=0.0002
μ
bar)
BAND CENTER FREQUENCIES, Hz
PKA-A12HA
PKA-A18HA
PKA-A12HAL
PKA-A18HAL
High
NOTCH
Low
43
SPL(dB)
36
LINE
UNIT
WALL
3.3ft
3.3ft
MICROPHONE