Meaning of decibel

dec•i•bel

Pronunciation: (des'u-bel", -bul), [key]
— n. Physics.
  1. a unit used to express the intensity of a sound wave, equal to 20 times the common logarithm of the ratio of the pressure produced by the sound wave to a reference pressure, usually 0.0002 microbar.
  2. a unit of power ratio, the number of units being equal to a constant times the logarithm to the base 10 of the intensities of two sources.
  3. a unit used to compare two voltages or currents, equal to 20 times the common logarithm of the ratio of the voltages or currents measured across equal resistances. Abbr.: dB, db
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.
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