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Hand-held Analyzer 2250 Light – User Manual182

Frequency Weighting

(contd.):

A ‘C-weighting’ curve is also used, particularly when evaluating very loud or

low-frequency sounds.

: 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.

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

the A-weighted equivalent continuous noise level.

Xeq,T,mov

and L

eq,T,mov

: Moving (or sliding) X-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

Xeq

at the start of the measurement as long as the

elapsed time less than or equal to T. Two values with frequency weighting

X = A and C are measured simultaneously. ∆L

eq,T,mov

is calculated as the

difference between L

Ceq,T,mov

and L

Aeq,T,mov

Xeq,T,mov,max

and

L

eq,T,mov,max

The maximum of the L

xeq,T,mov

values during the measurement, only taking

values into account where elapsed time is greater than or equal to T. Two

values with frequency weighting X = A and C are measured simultaneously.

∆L

eq,T,mov,max

is calculated as the difference between L

Ceq,T,mov,max

and

Aeq,T,mov,max

: 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.

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.

00005

Frequency

(Hz)

(dB)

10 20 50 100 200 500 1k 2k 5k 10k 20k

–20

–40

–60

1 2 ... 185 186 187 188 189 190 191 192 193 194 195 ... 211 212

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