# decibel

[ des-uh-bel, -buhl ]
/ ˈdɛs əˌbɛl, -bəl /

### noun Physics.

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.
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.
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. Abbreviation: dB, db

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## Origin ofdecibel

First recorded in 1925–30; deci- + bel1
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2021

## British Dictionary definitions for decibel

decibel
/ (ˈdɛsɪˌbɛl) /

### noun

a unit for comparing two currents, voltages, or power levels, equal to one tenth of a bel
a similar unit for measuring the intensity of a sound. It is equal to ten times the logarithm to the base ten of the ratio of the intensity of the sound to be measured to the intensity of some reference sound, usually the lowest audible note of the same frequency
Abbreviation: dB
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

## Medical definitions for decibel

decibel
[ dĕsə-bəl, -bĕl′ ]

### n.

A unit used to express relative difference in power or intensity, usually between two acoustic or electric signals, equal to ten times the common logarithm of the ratio of the two levels.

## Scientific definitions for decibel

decibel
[ dĕsə-bəl ]

A unit used to measure the power of a signal, such as an electrical signal or sound, relative to some reference level. An increase of ten decibels in the power of a signal is equivalent to increasing its power by a factor of ten. As a measure of sound intensity, a zero-decibel reference is stipulated to be the lowest level audible to the human ear; the speaking voice of most people ranges from 45 to 75 decibels.