Band sound power level
Band sound power level (of a source, in decibels)
Ten times the logarithm to the base 10 of the ratio of the mean value of the sound power produced by the source in the frequency band under consideration to the reference power (1 picowatt or 10-12 watt).
Please note that this is the term as it stands in the original IALA Dictionary edition (1970-1989)
International Association of Marine Aids to Navigation and Lighthouse Authorities - AISM