How to Calibrate a Sound Level Meter

Calibrating your Sound Level Meter before taking measurements

This post contains information about the best and easiest methods of performing a field (pre-measurement) calibration for your sound meter and other noise monitoring equipment. If you’re looking for traceable calibration, see our calibration and repair service.


Calibration Instructions Step by Step

  1. Locate your sound level meter, acoustic calibrator and barometer (barometer only required for calibrating Class 1 equipment where readings must be correct for atmospheric pressure according to IEC 60942).
  2. Turn on your sound meter and allow it to stabilise and acclimatise to the conditions that it will be used in. Navigate to the Calibration screen (at this point don’t start the calibration procedure).
  3. Carefully place the calibrator over the microphone capsule, ensuring not to twist either your sound meter or the calibrator as this can damage the microphone.
  4. Activate the calibrator at the desired tone, which is normally 94dB. Your calibrator may have a secondary tone, usually either 104dB or 114dB, which you may want to check your sound meter to as a reference after the calibration procedure.
  5. Within your sound meter again, press “OK” to begin the calibration procedure. Leave the calibrator on until the procedure has completed, normally between 5-20 seconds depending on the manufacturer and the model.
  6. The sound meter will notify whether it has passed or failed the calibration at this point. If passed, you’re good to go and perform your measurements.
  7. If the procedure fails, check that the calibrator is correctly attached to the microphone and is switched on at the desired level, then perform the calibration procedure again by removing the calibrator and starting from step 2.
  8. If you have checked the calibrator and sound meter and the calibration procedure continues to fail, it’s recommended that you contact either the sound meter manufacturer or a reputable calibration laboratory.

A last note – after you have completed your readings it is recommended that you check your sound meter against the calibrator to see if the accuracy has drifted. A calibration isn’t required but it’s important to make a note of any drift in your report.

Where can I purchase a Acoustic Calibrator / Sound Level Meter Calibrator?

Castle offer two different Triple Level Acoustic Calibrators:

These come with a Castle Certificate of Calibration as standard, but for an additional cost we also offer UKAS Calibration.

Castle Calibration and Repair Laboratory

There are 10 great reasons to use our Calibration and Repair Service which you can find out here.

Calibration service for sound meters

a part of the Castle Group of websites

Tel: 01723 584250
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