Noise Induced Hearing Loss
- Levels of Environmental Sounds
Source--Dangerous Level
dBA SPL
Produces Pain 
140-150 
Jet Aircraft During Takeoff (at 20 meters)
130
Discomfort Level
     Snowmobile
     Tractor Without Cab
120
Rock Concert
110
Die Forging Hammer
Gas Weed-Wacker
Chain Saw
Pneumatic Drill
100-105
Home Lawn Mowers
95 to 100 dB
Semi-trailers (at 20 meters)
90