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hearing for a healthy young person ranges from approximately 20Hz to 20000Hz (20kHz).
Frequency
weighting
Our hearing is less sensitive at very low and very high frequencies. In order to account for this,
weighting filters can be applied when measuring sound. The most commonly used weighting is the
'A-weighting', which approximates the human ear’s response to low - medium noise levels. A 'C-
weighting' curve is also used, particularly when evaluating very loud or low-frequency sounds.
LAE
Sound Exposure Level - sometimes abbreviated SEL and sometimes called Single Event Level, is the
Sound Exposure expressed as a level. The letter 'A' denotes that the A-weighting has been included.
LAeq
A widely used noise parameter that calculates a constant level of noise with the same energy con-
tent as the varying acoustic noise signal being measured. The letter 'A' denotes that the A-weighting
has been included and 'eq' indicates that an equivalent level has been calculated. Hence, LAeq is the
A-weighted equivalent continuous noise level.
LAF
The instantaneous time-weighted sound level, Lp, is available at any time. 'A' denotes that the A-fre-
quency weighting is used. 'F' denotes that the Fast time-weighting is used.
LAFmax
Maximum time-weighted sound level measured with A-frequency weighting and Fast time weight-
ing. It is the highest level of environmental noise occurring during the measurement time. It is often
used in conjunction with another noise parameter (for example LAeq) to ensure a single noise event
does not exceed a limit.
LAFmin
Minimum time-weighted sound level measured with A-frequency weighting and Fast time weight-
ing. It is the lowest level of environmental noise occurring during the measurement time (time res-
olution is 1s).
LA90.0
The noise level exceeded for 90% of the measurement period with A-frequency weighting. The
level is based on statistical analysis of LAeq sampled at 1 s intervals into 0.2 dB wide classes. The per-
centage is user-definable.
LAF(SPL)
The Sound pressure Level (maximum time-weighted sound level during the latest second) is avail-
able at any time. 'A' denotes that the A frequency weighting is used. ‘F’ denotes that the Fast time-
weighting is used.
LCpeak
Maximum peak sound level during a measurement. ‘C’ denotes that the C frequency weighting is
used. Used for assessing possible damages to human hearing caused by very high short-duration
noise levels.
Linear
Weighting
‘Linear’ frequency weighting is without any frequency weighting, that is, equivalent to LIN, Z or FLAT.
Linear
Time-averaged (RMS) weighted acceleration (or voltage) value, averaged over the entire meas-
urement period with frequency weighting Linear.
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