2250 Light – User Manual
178
Frequency Weighting
(contd.):
A ‘C-weighting’ curve is also used, particularly when evaluating very loud or
low-frequency sounds.
L
AE
:
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.
L
Aeq
:
A widely used noise parameter that calculates a constant level of noise with
the same energy content 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, L
Aeq
is
the A-weighted equivalent continuous noise level.
L
Aeq,T,mov
:
Moving (or sliding) A-weighted average (equivalent continuous noise level)
for the latest T minutes. Updated every second during measurement. The
parameter can be used to monitor the average noise level within T minutes,
for example, to monitor that the noise level during a music event doesn't
exceed a certain limit at any 15 minutes of observation time during the event.
The value is equal to L
Aeq
at the start of the measurement as long as the
elapsed time less than or equal to T.
L
Aeq,T,mov,max
:
The maximum of the L
Aeq,T,mov
values during the measurement, only taking
values into account where elapsed time is greater than or equal to T.
L
AF
:
The instantaneous time-weighted sound level, Lp, is available at any time.
‘A’ denotes that the A-frequency weighting is used. ‘F’ denotes that the Fast
time-weighting is used.
L
AFmax
:
Maximum time-weighted sound level measured with A-frequency weighting
and Fast time weighting. 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 L
Aeq
) to ensure a single noise event
does not exceed a limit.
L
AFmin
:
Minimum time-weighted sound level measured with A-frequency weighting
and Fast time weighting. It is the lowest level of environmental noise occurring
during the measurement time (time resolution is 1 s).
000055
Frequency
(Hz)
0
Lp (dB)
10
20
50
100 200 500
1k
2k
5k
10k 20k
–20
–40
–60
A
C
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