Appendix
Typical 'A' Weighted dB levels
140
120
100
50 HP Siren (100')
130
110
Jet take-off (200')
Riveting machine
Chain saw
Subway (20')
90
70
Boiler room
Pneumatic drill (50')
Vacuum cleaner (10')
Large store
80
60
Freight train (100')
Speech (1')
Large Office
Residence
50
30
10
Small office
40
Residential area
(night)
Sound studio
Whisper (5')
20
0
Threshold of hearing
Frequency Weighting Graph
Frequency Weighting
5
0
-5
-10
-15
-20
-25
-30
-35
-40
-45
'A' Weighting
'C' Weighting
10
100
1000
10000
Frequency (Hz)
7
407768 Version 2.0 06/06