Extech Instruments 407768 User Manual page 7

Appendix
Typical 'A' Weighted dB levels
50 HP Siren (100')
Jet take-off (200')
Riveting machine
Subway (20')
Pneumatic drill (50')
Vacuum cleaner (10')
Large store
Small office
Residential area
(night)
Whisper (5')
Threshold of hearing
Frequency Weighting Graph
5
0
-5
-10
-15
-20
-25
-30
-35
-40
-45
10 100
Frequency (Hz)
Air Concern Ltd, Building 173 Curie Avenue Harvell Didcot, Oxfordshire
140
130
120
110
Chain saw
100
90
Boiler room
80
Freight train (100')
70
Speech (1')
60 Large Office
Residence
50
40
30
Sound studio
20
10
0
Frequency Weighting
1000 10000
more infor for
Phone: 01235 838 555
Email: cs@airconcern.co.uk
Web. www.airconcern.co.uk
'A' Weighting
'C' Weighting
Extech 407768