decibel
Sign in to saveThe 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
Article
38 sectionsContents
- 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 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 ).
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").