What is Decibel?
For the layman, this means the basic unit of sound. However, scientifically, Decibel (abbreviated as dB) is a dimensionless unit for expressing the ratio of two powers or two pressures or two intensities in a logarithmic way. One bel is equal to 10 decibels.
The levels corresponding to sound pressure, sound intensity and sound power are respectively: sound pressure level (SPL), sound intensity level (SIL) and sound power level (SWL or PWL). These are expressed in units of dB. While evaluating these levels international accepted values are taken as reference standards.