Source: 
web site; www.cdc.gov
Noise Meter
Play around with the Noise Meter and hear the different sounds and sound intensities of everyday objects. The red bar below shows how long it takes before a particular sound level becomes dangerous to the human ear. For example, a chain saw has a sound intensity of about 110 dB. Without proper hearing protection, running a chain saw for only 2 minutes can become dangerous to the human ear!
Here is the meter: You can use it on this site, or download to your computer.
http://www.cdc.gov/niosh/topics/noise/abouthlp/noisemeter_flash/soundMeter_flash.html