Instruction Manual

Sound Level Meter Types 2245 – Instruction Manual Page 15 of 110
2.4 Calibration
Calibration is an adjustment of your sound level meter to measure and display correct
values. The sensitivity of the microphone as well as the response of the electronic
circuitry can vary slightly over time or could be affected by environmental conditions
such as temperature and humidity. While you are unlikely to ever experience a large
drift or change in sensitivity with the sound level meter, it is nevertheless good practice
to perform regular checks of the calibration, normally before and after each set of
measurements.
It is strongly recommended that Brüel & Kjær Sound Calibrator Type 4231 is used.
2.4.1 Calibration Procedure
The sound level meter requires a stable signal of either 94 dB or 114 dB. Use Sound
Calibrator Type 4231. It provides a stable sound pressure at 1 kHz and has minimal
susceptibility to environmental factors. The calibration procedure is semi-automatic:
you just need to select calibration mode and mount and switch on the calibrator, then
the sound level meter will calculate the sensitivity.
To perform acoustic calibration:
1. Stand away from loud sound sources that may interfere with the calibrator’s
signal.
2. Switch on the sound level meter.
3. Press the POWER/MENU/SELECT button and the arrow buttons to
navigate to System settings > Advanced settings and set Service mode to
Enabled .