X Y Z
Sound Exposure: Definitions, Terms, Units and Parameters - 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 E A.
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%
2 Pa² = 88.0 LAeq,8 h
5 Pa² = 91.9 LAeq,8 h
10 Pa² = 94.8 LAeq,8 h
see also :
Exposure Action Value : EAV and
Exposure Limit Value : ELV
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.
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.
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.
Also known as PSEM - Personal Sound Exposure Meter.
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.
Sound Exposure Time : the time a person is exposed to noise during a workday - used for calculation of L EP,d - Daily Personal Noise Exposure.