# dB

## Definitions

### Electronics

- A dimensionless logarithmic
__unit__ utilized to express the __ratio__ of two powers or intensities, such as voltages, currents, or sound intensities. The number of decibels is equal to 10 times the __common logarithm__ of the ratio of the measured powers, or when comparing voltages, currents, or analogous acoustic quantities, it is 20 times the common logarithm. It is equal to 0.1 bels, or approximately 0.1151 nepers. - In acoustics, the
__sound pressure__ __ratio__ that determines the relative intensity of sounds, against a __reference pressure__. Such a __pressure__ is usually defined as 20 micropascals, which is assigned a value of 0 decibels. Anything above this 0 decibels threshold is considered to be audible. Before pain sets in, a person with good hearing can listen at 120 decibels, or 20 pascals, which is a __trillion__ times louder than 0 decibels. - chemical symbol fordubnium
(written as *Db*)

- synonymdecibel

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