Soundproofing glossary definition of level average

level average :

In acoustics, logarithm of the ratio of a quantity to a reference quantity of the same kind. The base of the logarithm (always ten, unless otherwise specified), the reference quantity, and the kind of level shall be specified. Examples of kinds of levels are sound power level and sound intensity level. For common logarithms on the base ten, the symbol for logarithm is "lg."