THE CLASS SYSTEM FOR NOISE LEVEL PRODUCTION Under the Australian and New Zealand Standard AS/NZS1270, hearing protectors are tested against a range of noise frequencies and a Sound Level Conversion 80 (SLC80) rating obtained. SLC 80 is a rating defined as the difference between the sound level of the environment and the level of the sound actually heard when the hearing protection is being used. The resulting dB level is the level of sound getting through when the protector is used.
Noise-induced hearing loss is caused by prolonged exposure to loud noise. The noise damages inner ear hair cells, causing hearing loss to deteriorate over time and become permanent. Noise-induced hearing loss is largely preventable.
AVERAGE EXPOSURE DB(A) OVER 8 HOURS
SLC80 DB(A) RANGE
CLASS
1
Less than 90
10 to 13
2
90 to less than 95
14 to 17
3
95 to less than 100
18 to 21
4
100 to less than 105
22 to 25
5
105 to less than 110
26 or greater
NOISE LEVEL COMPARISONS
DECIBEL LEVEL DECIBEL EFFECT
NOISE SOURCE
Jet take-off (at 25 meters)
150 Eardrum rupture
Aircraft carrier deck
140 Eardrum rupture
Military jet aircraft take-off from aircraft carrier with afterburner at 15m (130 dB)
130 Eardrum rupture
Thunderclap, chain saw. Oxygen torch (121 dB)
120 Painful. 32 times as loud as 70 dB
Steel mill, auto horn at 1 meter. Turbo-fan aircraft at takeoff power at 65m (118 dB). Riveting machine (110 dB); live rock music (108 - 114 dB) Jet take-off (at 305 meters), use of outboard motor, power lawn mower, motorcycle, farm tractor, jackhammer, garbage truck. Boeing 707 or DC-8 aircraft at one nautical mile (1900m) before landing (106 dB); jet flyover at 300m (103 dB); Bell J-2A helicopter at 30m (100 dB) Boeing 737 or DC-9 aircraft at one nautical mile (1900m) before landing (97 dB); power mower (96 dB); motorcycle at 8m (90 dB). Newspaper press (97 dB) Garbage disposal, dishwasher, average factory, freight train (at 15 meters). Car wash at 6m (89 dB); propeller plane flyover at 300m (88 dB); diesel truck 65km at 15m (84 dB); diesel train at 70km at 30m(83 dB). Food blender (88 dB); milling machine (85 dB) Passenger car at 105km at 7m (77 dB); freeway at 15m from pavement edge 10 a.m. (76 dB). Living room music (76 dB); radio or TV-audio, vacuum cleaner (70 dB)
110 Average human pain threshold. 16 times as loud as 70 dB
100 8 times as loud as 70 dB. Serious damage possible in 8hr exposure
90 4 times as loud as 70 dB. Likely damage in 8 hour exposure
80 2 times as loud as 70 dB. Possible damage in 8 hour exposure
70 Arbitrary base of comparison. Upper 70s are annoyingly loud to some people
Conversation in restaurant, office, background music, Air conditioning unit at 30m
60 Half as loud as 70 dB. Fairly quiet
Quiet suburb, conversation at home. Large electrical transformers at 30m
50 One-fourth as loud as 70 dB
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