Typically, in real world circumstances, sound levels vary considerably over time. The Leq is the energy average sound level over a monitoring time interval. It is a hypothetical continuous sound level that contains the same sound energy as the actual sound occurring during the time interval. The letter symbol Leq typically implies A-weighting, i.e., the energy average sound level in dBA. Also the duration of measurement is typically stated, e.g., Leq (1 hour).