A decibel is the unit used to measure the intensity of a sound. It is abbreviated as dB. On the decibel scale, the smallest sound that can be heard is 0 dB. This is close to total silence. A sound that is ten times the intensity of 0 dB is rated as 10 dB. A sound 100 times in intensity is 20 dB, a sound 1000 times in intensity is 30 dB, and so on. Our normal conversation is 60 dB. When you mow the lawn the sound of the lawnmower is 90 dB. Have you ever attended a rock concert? The sound there can get as high as 120 dB. A firecracker set off on Independence Day comes in at 140 dB.
Any sound above 85 dB can cause hearing loss. The amount of hearing loss depends not just on the intensity of the sound, but also on how long you are exposed to the sound. If you are anywhere that you need to raise your voice for others to hear you, you will know that the sound around you is at least 85 dB.