What causes NIHL?
NIHL can be caused by a one-time exposure to an intense “impulse” sound, such as an explosion, or by continuous exposure to loud sounds over an extended period of time, such as noise generated in a woodworking shop.
Sound is measured in units called decibels. Sounds of less than 75 decibels, even after long exposure, are unlikely to cause hearing loss. However, long or repeated exposure to sounds at or above 85 decibels can cause hearing loss. The louder the sound, the shorter the amount of time it takes for NIHL to happen.
Here are the average decibel ratings of some familiar things:
The humming of a refrigerator
45 decibels
Normal conversation
60 decibels
Noise from heavy city traffic
85 decibels
Motorcyles
95 decibels
An MP3 player at maximum volume
105 decibels
Sirens
120 decibels
Firecrackers and firearms
150 decibels