Definition of Decibel

A decibel (dB) is a unit of measurement that gages the intensity of sound. The units define how loud a noise source is, ranging on a comparative scale from 0-194. A dB reading of “0” indicates the faintest sound the human ear can detect, while a dB reading of “180” would be the equivalent to standing on a rocket pad during launch.

Your average day is filled with sound sources that typically range from 30-100 dB. Daytime hours average 10 dB more sound pressure than night time hours. Conversational voice levels average a 65 dB rating, while OSHA demands hearing protection for factory workers exposed over an 8 hour period to levels stronger than 85 dB. The pain threshold for human ear starts at about 120 dB. Our dB-Chart illustrates a variety of sound sources and their corresponding dB levels in a variety of Commercial, Industrial and Residential settings:

Decibel Level Scale Comparison Chart

The decibel scale is logrithmic, not linear. This simply means that for every 3 decibels you move up or down the scale from 0-194, you are adding or dropping 50% of your remaining sound pressure levels to your exposure. By dropping 6 decibels, for instance, you first move 3 dB, and then another 3 dB. For each 3 dB you drop, your sound pressure levels will drop another 50% of the remaining sound pressure.   The following table will help illustrate the order of magnitude associated with dB.


dB-Drop                       Survival Rate

1 dB Drop                     79% of your noise has survived
3 dB-Drop                     50% of your noise has survived
6 dB-Drop                     25% of your noise has survived
9 dB-Drop                     12.5% of your noise has survived
10 dB-Drop                   10% of your noise has survived
20 dB-Drop                   1% of your noise has survived
30 dB-Drop                   .01% of your noise has survived

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