3M SE, DL user manual Calibrate, Calibration screen, Pre-Calibration, Post-Calibration

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Calibrate

Calibration screen

Calibrate

3M recommends calibrating your Verifier before you run a STI-PA measurement and after to ensure highly accurate measurement results.

The microphone should be calibrated before use for a number of reasons. First, the microphone is sensitive to humidity and pressure changes. Calibrating before taking measurements assures that your level measurements are accurate for the current environment. Performing a calibration verification (post-cal) allows you to verify that conditions have not significantly affected your readings.

Calibrating also serves the dual purpose of checking the microphone for significant damage, such as a torn or contaminated diaphragm.

You can calibrate the instrument in the field with reference to the output of a calibrated sound source. 3M offers a line of acoustic calibrators that are available (such as the QC10/20).

Calibration screen

The Calibration screen contains a calibration option, called Calibrate, and a Calibration History. The history shows Pre-Calibration (Pre-Cal) and Post- Calibration (Post-Cal) results for previous calibrations, as applicable. For each calibration type, the resulting SPL level is shown along with the time and the date of the calibration.

Pre-Calibration

The main reason to calibrate is to adjust the current microphone reading to match a reference input, usually provided by a calibrator.

A Pre-Calibration is conducted when the session is stopped. When you calibrate during a stopped session, the new calibration results replace the previous Pre-Calibration results and the Post-Calibration results are removed. You will always see the last Pre- Calibration results.

Post-Calibration

A post-cal is really a calibration verification; that is, it does not change the instrument’s calibration. It compares the microphone's current level with the value read from the last calibration (assuming that the same source is used).

A Post-Calibration is a calibration done during a session pause. When you

Models SE and DL