PART 1
English
19
3) Switch on the sound level meter. The L
AF
parameter is displayed (L
A
, Fast). If the meter
is already switched on and another parameter displayed, press until L
A
is displayed.
4) Press to select the 60– 140 dB sound level range (if not already displayed). This is the
sound level meter’s reference range and should be used for calibration.
5) Switch on the calibrator. Type 4231 automatically emits a 1 kHz signal at 94 dB. Wait
approximately 5 seconds for all levels to stabilise.
6) Using the supplied screwdriver on the calibration switch located on Type 2240’s side panel,
adjust your sound level meter to display 93.9 dB
1
.
Fig.4.2
Adjusting calibration using
the screwdriver on the
calibration switch located
on Type 2240’s side panel
1The reading should be 93.9dB (not 94 dB) to agree with your sound level meter's microphone (Type 4188
free-field microphone). The 94 dB level specified for the calibrator is the pressure field in the coupler when
the calibrator is fitted to the sound level meter. A slight correction must, therefore, be applied. This is
explained in the calibrator's manual and the calibration chart supplied with your microphone.
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