decibel

DES-ih-bel /ˈdɛsɪbɛl/
nounB2SATACTTOEFL
technicalscientific

A logarithmic unit used to measure the intensity of a sound or the power level of an electrical signal.

Abbreviated as 'dB', the decibel is not an absolute unit of measurement like an inch or a pound; instead, it measures a ratio of sound pressure or signal level relative to a reference point.

The story behind the word. The unit was created by the Bell Telephone Laboratories to measure signal loss in telephone lines. They named the base unit the 'Bel' in honor of their founder, Alexander Graham Bell. Because a Bel is quite large, engineers typically use one-tenth of a Bel—hence, a 'deci-bel.'

Word relationships

  • dB: The standard scientific and industry abbreviation.

Commonly confused with

  • frequency: Decibels measure the amplitude or volume of a sound, while frequency (measured in Hertz) measures the pitch of a sound.

Collocations

  • decibel scale
  • decibel level
  • peak decibels
  • decibels of gain

Example sentences

  • "Prolonged exposure to sounds above 85 decibels, such as heavy city traffic or loud lawnmowers, can cause permanent hearing loss." A health warning about hearing damage.
  • "The engineer pulled the vocal track down by three decibels to make room for the snare drum's transient peak." A technical mixing manual.

Memory hook

Think of 'deci-' (like decimal or decade, meaning ten) and 'Bell' (like a ringing bell)—ten steps of sound on a bell. Decibel is one-tenth of a Bell, measuring sound volume.

When not to use

Avoid using decibels as a linear scale; because it is logarithmic, an increase of 10 dB represents a sound that is physically ten times more powerful, and subjectively twice as loud.

Fun facts

  • A whisper is about 30 decibels, normal conversation is 60 decibels, a rock concert is 120 decibels, and a jet engine up close is a painful 140 decibels.

Related words

gain, fader, acoustics

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