Definition

1. Noun:
   • A unit for measuring the relative intensity of sound: The decibel is a logarithmic unit used to express the ratio between two values of a physical quantity, most commonly sound pressure level or power. It indicates how loud a sound is relative to a reference level.
   • A unit for measuring ratios of power or amplitude in electronics and acoustics: While most commonly associated with sound, the decibel is a general unit for expressing ratios, such as signal gain or loss.

Usage Examples

• Noun:

Advanced Usage

• "Decibel level": A common phrase referring to the measured intensity of sound.
• Used in comparative expressions: Decibels are inherently comparative, measuring one intensity against a standard reference.

Variants and Related Words

• dB: The standard abbreviation for decibel.
• Bel: The larger unit from which the decibel is derived; one decibel is one-tenth of a bel. This term is rarely used in practice.

Synonyms

• Sound level unit: A more general descriptive term.
• dB (abbreviation): The direct abbreviated form.

Notes on Meaning

• Not an absolute unit: A decibel is not a fixed amount like a meter or a kilogram. It is a logarithmic ratio. A 10-decibel increase represents a tenfold increase in sound intensity, while a 20-decibel increase represents a hundredfold increase.
• Reference intensity: For sound in air, the common reference is the quietest sound the average human ear can hear, which is defined as 0 decibels.

Noun

1. a logarithmic unit of sound intensity; 10 times the logarithm of the ratio of the sound intensity to some reference intensity