decibel

Also known as dB

The decibel (symbol: dB) is a relative unit of measurement equal to one tenth of a bel (B). It expresses the ratio of two values of a power or root-power quantity on a logarithmic scale. Two signals whose levels differ by one decibel have a power ratio of 101/10 (approximately ) or root-power ratio of 101/20 (approximately ).

AI overview

A decibel is a unit of measurement that compares two amounts—such as sound power or electrical power—using a logarithmic scale, making it easier to express very large or very small ratios in manageable numbers. It matters because it allows us to describe phenomena like sound levels, signal strength, and power differences in a practical way, where a one-decibel difference represents a specific mathematical ratio between the two values being compared.

AI-generated from the Wikipedia summary — may contain errors.

Key facts

Unit.name: decibel
Unit.standard: Non-SI accepted unit
Unit.symbol: dB
Unit.namedafter: Alexander Graham Bell
Unit.units1: bel
Unit.inunits1: 0.1 bel

via Wikipedia infobox

Wikidata facts

Show 5 more facts

Unicode character: ㏈
Stack Exchange tag: stackoverflow.com/tags/decibel
unit symbol: dB
conversion to standard unit: 0.1
Commons category: Decibel

Sources (2)

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~51 min read

Article

38 sections

Contents

History
Definition
Power quantities
Root-power (field) quantities
Relationship between power and root-power levels
Conversions
Examples
Properties
Reporting large ratios
Representation of multiplication operations
Representation of addition operations <span class="anchor" id="Addition"></span>
Fractions
Uses
Perception
Acoustics
Telephony
Electronics
Optics
Video and digital imaging
Suffixes and reference values <span class="anchor" id="Suffixes"></span>
List of suffixes
Voltage
Acoustics
Audio electronics
Radar
Radio power, energy, and field strength
Antenna measurements
Other measurements
List of suffixes in alphabetical order
Unpunctuated suffixes
Suffixes preceded by a space
Suffixes within parentheses
Other suffixes
See also
Notes
References
Further reading
External links

The strict original usage above only expresses a relative change. However, the word decibel has since also been used for expressing an absolute value that is relative to some fixed reference value, in which case the dB symbol is often suffixed with letter codes that indicate the reference value. For example, for the reference value of 1 volt, a common suffix is "V" (e.g., "20 dBV").