Decibel :

Decibel (dB) is a logarithmic unit, describing a ratio. It is used to express the ratio of either of the physical quantity, power or intensity. One decibel is one tenth of one bel. In the early 20th century, the term defines the measure of power of telephony. In the modern sense, it is used in science and different sections of engineering like acoustics, electronics, and control theory. It is also a unit used in the measurement of sound level.