Description: Sound pressure level is actually a ratio of the absolute Sound Pressure and a reference level (usually the Threshold of Hearing or the lowest intensity sound that can be heard by most people).; Name: acoustic pressure level
Description: Ten times the logarithm to the base 10 of the ratio of the square of the sound pressure, p, to the square of a reference value, p0, expressed in decibels; Name: Sound pressure level
Description: passed time period after comissioning of a system, sub-system, component or piping; Name: Operating time 