It doesn’t matter how much you would like to ascribe a special meaning to it, this one is very clear in it’s meaning. : a subjective device of loudness for an average listener equivalent on the loudness of a 1000-hertz sound that has an intensity 40 decibels above the listener's https://alleideenforum.de/markisen-in-wien-perfekter-sonnenschutz-fur-ihr-zuhause/