Chapter 3 – Taking Measurements
Measurement Settings
BB 1219 – 11
31
Integrating Sound Level Meter Type 2239 A
User Manual
3.4.3 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 according to which you are measuring. If no time
weighting is specified, then use 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 six 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),
● CF (“C” frequency weighted and Fast time weighted),
● CS (“C” frequency weighted and Slow time weighted), or
● CI (“C” 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.
To Change the Time Weighting:
1. Make sure measurement has stopped (as shown in Fig. 3.8).
If the instrument is measuring, then press
to stop it.
2. Press until the Time Weighting Set-up Window is vis-
ible on the screen, as shown below.
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