**Sound Exposure** is the time integral of the sound pressure squared. The SI unit of *sound exposure* is the pascal-squared-hour (Pa^{2}·h)

For a given period of time, an increase of 10 dB(A) in sound pressure level corresponds to a tenfold increase in the **sound exposure**.

1 Pa²·h = 100% Dose = 85 LAeq(8 h) = 85 dBA for 8 hours.

0.1 Pa² = 74.9 LAeq,8 h

0.2 Pa² = 78.0 LAeq,8 h

0.5 Pa² = 81.9 LAeq,8 h

1 Pa² = 84.9 LAeq,8 h = 100% Dose

2 Pa² = 88.0 LAeq,8 h

5 Pa² = 91.9 LAeq,8 h

10 Pa² = 94.8 LAeq,8 h

0.2 Pa² = 78.0 LAeq,8 h

0.5 Pa² = 81.9 LAeq,8 h

1 Pa² = 84.9 LAeq,8 h = 100% Dose

2 Pa² = 88.0 LAeq,8 h

5 Pa² = 91.9 LAeq,8 h

10 Pa² = 94.8 LAeq,8 h

**Sound Exposure Action Value : EAV** is the 8-hour daily *noise exposure* above which employers are required to take action to control exposure. There are two action levels :

**Sound Exposure Limit Value : ELV** is the maximum *noise exposure* employees may be exposed to on any single 8-hour day. The daily or weekly exposure is 87 dBA and a
Peak -
Sound Pressure of 140 dBC.

Sound Exposure Definition : time integral of squared instantaneous A-weighted, sound pressure, over a stated period of time or event. The frequency weighting may be other than A, if so specified. (IEC 801-21-23)

● Note 1 : duration of integration is implicitly included in the integral, and need not be reported explicitly.

● Note 2 : the unit of *sound exposure* is the pascal-squared-second (Pa^{2}·s), if time is in seconds and the pascal-squared-hour (Pa^{2}·h), if time is in hours.

**Most modern sound level meters measure sound exposure and then calculate the required parameters.**

To see a range of Noise at Work Meters click here.

**Sound Exposure Level : SEL** is the constant sound level that has the same amount of energy in one second as the original noise event. A-weighted *sound exposure levels* are denoted by the symbol **LAE**.

**Sound Exposure Level** is similar to
Leq - equivalent continuous sound level as the total
sound energy is integrated over the measurement period. However instead of averaging over the measurement period, a reference duration of 1 second is used.

It follows that the **sound exposure level** = Leq + 10·Log10T where T is in seconds for the whole measurement period.

● Note : Log10 is also written as lg = logarithm to the base 10; recommended by ISO the International Standards Organisation.

**Sound Exposure Level** is numerically equivalent to the total Sound Energy.

For example a noise level of 90 dBA lasting 1 second would have a *SEL* of 90 dBA but if the event lasted 2 seconds the *SEL* would be 93 dBA.

Put another way if a second event of 80 dBA occurred it would have to last 10 seconds to register a 90 dBA SEL.

**Sound Exposure Level** Leq and Dose are mathematically related if the Time is known.

**Sound Exposure Levels** normalized to 1 second are a very useful way of comparing different sound events and sources.

Sound Exposure Level Definition : logarithm of the ratio of a given time integral of squared A-frequency weighted sound pressure, over a stated time interval or event such as an aircraft flyover, to the product of the squared reference sound pressure of 20 μPa and the reference duration of one second. *Sound exposure level* in decibels is ten times the logarithm to the base ten of that ratio. The reference sound pressure and the frequency weighting may be different, if specifically stated with the *sound exposure level* (IEC 801-22-17)

See also : Single Event Noise Exposure Level and the IEC Definition of Level

**Sound Exposure Meter** a small instrument designed to be worn by an individual to provide a measure of the accumulated sound exposure received by the wearer while moving about during the workday.

The instrument is calibrated in Pa²·h. If the meter is worn for only a representative part of the working day, the reading must be corrected appropriately.

Also known as PSEM - Personal Sound Exposure Meter.

Noise Dosimeter (or dosemeter) is a more general term for instruments having a similar purpose but may be calibrated to suit differing standards around the world.

**Sound Exposure Time** the time a person is exposed to noise during a workday - used for calculation of LEP,d the Daily Personal Noise Exposure.

See also : Noise Dose • Leq - Equivalent Continuous Sound Level