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The '''decibel''' is the unit of sound [[pressure]] used to measure [[noise]]. Decibel means 1/10 of a Bel, after [[Alexander Graham Bell]]. Because decibels are such a small measure, they are computed [[logarithm]]ically and cannot be added arithmetically. An increase of ten dB is perceived by human [[ear]]s as a doubling of noise. There is no absolute decibel scale, so the decibel is used to measure sound in comparison to another sound.

The '''decibel''' ('''dB''') is a logarithmic unit, often used to measure of sound [[pressure]]. Decibel means 1/10 of a Bel, after [[Alexander Graham Bell]]. There is no absolute decibel scale, so the decibel is used to measure sound in comparison to another sound, i.e, the 0 dB reference. This  is defined as a sound pressure level of .0002 microbar, or 20 micropascals: commonly the threshold of hearing a sound with a frequency of 1 KHz.

[[category:Units of Measurement]][[category:physics]]

[[category:Units of Measurement]][[category:physics]]