Originally Posted by
gmdboston
The threshold of pain is about 120dba, and varies some depending on the frequency. Normal conversation is about 60-65 dba.
Here are some examples:
0-Faintest sound heard by human ear.
30-Whisper, quiet library.
60-Normal conversation, sewing machine, typewriter.
90-Lawnmower, shop tools, truck traffic; 8 hours per day is the maximum exposure to protect 90% of people.
100-Chainsaw, pneumatic drill, snowmobile; 2 hours per day is the maximum exposure without protection.
115-Sandblasting, loud rock concert, auto horn; 15 minutes per day is the maximum exposure without protection.
140-Gun muzzle blast, jet engine; noise causes pain and even brief exposure injures unprotected ears. Maximum allowed noise with hearing protectors.
Note that Zero is the faintest sound detectable by the human ear. This means sound waves can have negative db ratings, but they are too quiet for us to hear them.