**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 normally based on an exchange rate of 3. An 8-hour Leq is also known as LEP,d = LEX,8h.

**Leq** is the 'common' name for the *Equivalent Continuous Sound Level,* see the formal IEC definition directly below

● Note 1 : if a frequency weighting is not specified, the A-frequency weighting is understood.

● Note 2 : in principle, exponential time weighting is not involved.

**Not to be confused with IEC 801-22-11, equivalent continuous sound pressure level**

*Equivalent Continuous Sound Level* is also known as the *Leq*

*Equivalent Continuous Sound Level* is also known as the *Time-average Sound Level (LAT)*

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, Sound Pressure Level.

LCeq : C-weighted, Leq, Sound Pressure Level

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

Noise Dose

Sound Energy

Sound Level and Integrating Sound Level Meters

Sound Exposure

Sound Pressure

See also • the IEC Definition of Level

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