The decibel is a relative unit of measurement equal to one tenth of a bel.
Logarithmic unit expressing the ratio of a physical quantity
A unit used to express relative difference on power, usually between acoustic or electric signals, equal to ten times the common logarithm of the ratio of the two level.
A common measure of sound intensity ratio that is one tenth of a bel on the logarithmic intensity scale. It is defined as dB = 10 log10(P1 / P2), where P1 and P2 are the relative powers of the sound.