Every sound has a level in decibels that relates its loudness. For example, a hair dryer can be about 53 decibels (dB(A)) while a chainsaw from three feet away is about 117 dB(A).
The decibel comes from the unit of measurement of sound intensity and was named after inventor and scientist Alexander Graham Bell. A decibel is one tenth of a bel. The human ear responds to sounds at different frequencies so three levels are used dB(A), dB(B) and dB(C). The most commonly used is dB(A).
To measure the intensity of a sound, a measurement was needed that would provide them with quantifiable data that can be compared and contrasted. A chainsaw may sound louder or quieter from one person to another depending on their hearing a ability. This measurement is created using mathematics and is free of human error and perspective.
Every sound has a decibel level associated with it. If an item is 52 dB(A), then it has a sound similar in intensity to a electric fan, hair dryer, a running refrigerator and a quiet street. Other common sounds include a blender at 90 dB(A), diesel truck 100 dB(A) and a crying baby can reach 110 dB(A).