WHO	World Health Organization
EU	European Union
SPL	Sound Pressure Level
$L_{Aeq}$	A-weighted equivalent sound level
LAN	A-weighted Sound Pressure Level exceeded for N percent of the time
LAF	A-weighted Sound Pressure Level measured with a fast time-constant
$Ld$	Day Noise Level. A-weighted Leq, over the 14-h day period (7 to 21)
$Le$	Evening Noise Level. A-weighted Leq, over the 2-h evening period (21 to 23)
$Ln$	Night Noise Level. A-weighted Leq, over the 8-h night period (23 to 7)
$L_{den}$	Day–evening–night noise level. A-weighted Leq, over a whole day, but with a penalty
	of 10 dBA for nighttime noise (23 to 7) and 5 dBA for evening noise (21 to 23)