Most community and industrial noise measurements are A-weighted so the LAeq descriptor is used
Early sound level meters had a very limited dynamic range, so if the noise levels fluctuated by more then 20 dB during a measurement the accuracy was in doubt. They also used exponential averaging circuits (Fast, Slow etc.) which helped the operator average the meter fluctuations by eye, but introduced another accuracy limitation.
Modern integrating sound level meters monitor a wide range of fluctuating levels faithfully and the digital linear averaging circuits record and display the Leq (average energy) time histories and the statistical noise levels, over minutes, hours or days as required.
Leq is widely used, but not widely understood - click here for a more detailed explanation.
Leq is the 'common' name for the equivalent continuous sound level, see the IEC definition below
Leq. equivalent continuous sound level is also known as the time-averaged sound level and should not to be confused with the equivalent continuous sound pressure level. To compare these definitions directly click here
See also •
Integrating Sound Level Meters
Leq : Equivalent Continuous Sound Level - the more detailed explanation
SEL : Sound Exposure Level = Leq normalised to 1 second, equivalent to the total Sound Energy.
Related Terms •
CNEL : Community Noise Equivalent Level
LAIeq : A-weighted, Impulse, Leq.
LCeq : C-weighted, Leq.
Lday : Day equivalent level
Lden : Day-evening-night equivalent level
Ldn : Day-night equivalent level
LEX,8h : Daily Exposure Level
LEP,d : Daily Personal Noise Exposure
LEP,w : Weekly Personal Noise Exposure
Sound Level and Integrating Sound Level Meters
See also • the IEC Definition of Level