|Definition:|| logarithm of the ratio of a given quantity to a reference quantity of the same kind. The base of the logarithm, the reference quantity, and the kind of level must be indicated
NOTE 1 – The kind of level is indicated by use of a compound term such as sound power level or sound pressure level.
NOTE 2 – The value of the reference quantity remains unchanged, whether the chosen quantity is peak, root-mean-square, or otherwise.
NOTE 3 – The base of the logarithm is indicated by use of a unit of level associated with that base.