BB106411.book : 2237-ch3 Black 15
Chapter 3 – Taking Measurements
Making Measurement Settings
BB1064–11
3–15
2237 Controller
User Manual
time, then sound levels are too soft; select a lower meas-
urement range. If the display ever becomes full and the
value for the upper limit of the measurement range
changes to read “OVL”, then sound levels are overloading
the instrument; select a higher range.
3.4.2 Setting the Time Weighting
The time weighting adjusts how quickly the sound level meter
reacts to sudden changes in sound pressure level. Three time
weightings are available, each of which is defined in the IEC
and ANSI standards.
● F (Fast): uses a 125 ms time constant. This setting is used
in most situations
● S (Slow): uses a 1 s time constant, which smooths out
fluctuating levels
● I (Impulse): uses a 35 ms time constant with a slow decay,
which allows readings of short-duration sound events.
The time weighting you choose will usually depend on the
regulations for which you are measuring. If no time weighting
is specified, then use the Fast weighting.
The current time weighting setting is displayed in the Meas-
urement Window. It appears in the bottom left-hand corner.
It will show one of three values:
● AF: “A” frequency weighted and Fast time weighted
● AS: “A” frequency weighted and Slow time weighted
● AI: “A” frequency weighted and Impulse time weighted
In Fig. 3.8, the current setting is shown to be AF, so a fast
time weighting has been set.
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