Play around with the Noise Meter and hear the different sounds. 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 level of about 110 dB. Without proper hearing protection, running a chain saw for only 2 minutes can become dangerous to your hearing!
With permission of the National Institute of Occupational Safety and Health (NIOSH).
For more information on standards for noise exposure, see Occupational Noise Exposure, DHHS (NIOSH) Publication No. 98-126