Definitions, Related Terms and Parameters:
Sound Exposure - see also Noise Dose
Sound Exposure is the A-weighted, Sound Pressure, squared and integrated over a stated period of time or event.
The SI unit is Pa² s however the practical unit used in Noise Dosimeters
(sound exposure meters) is Pa² h.
For a given period of time, an increase of 10 dB(A) in Sound Pressure Level
corresponds to a tenfold increase in EA
1 Pa² h = 100 Dose% = 85 LAeq(8 h) = 85 dBA for 8 hours - see also sound
Exposure Action Value : EAV
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
* Most modern sound level meters measure sound exposure and then calculate the required parameters.
Sound Exposure Level : SEL
: is the logarithmic measure of the A-weighted , Sound Pressure Level
squared and integrated over a stated period of time or event, relative to a reference sound pressure value. The units are the decibel (dBA).
In practice the SEL normalized to a 1 second period was found to be extremely useful when comparing noise levels so this is now commonly used and also referred to as the Sound Exposure Level
Sound Exposure Level : SEL
is any Leq
noise level or event 'commonly' normalized to 1 second.
SEL = Leq + 10·Log10
T where T in seconds. Log10 is also written as lg = logarithm to the base 10
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
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.
See also Single Event Noise Exposure 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.
Noise dosemeter (or dosimeter) is a more general term for instruments having a similar purpose but may be calibrated to suit differing standards around the world.
Also known as PSEM - Personal Sound Exposure Meter.
Leq - Equivalent Continuous Sound Level
Certified Sound Exposure Instrumentation
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