There are four types of frequency corrections in the Nor145.
Random incidence correction
Windscreen correction
Frequency response correction
The three upper corrections must be applied carefully because they will directly influence the measurement result.
The Random incidence and Windscreen corrections are automatically turned off during calibration.
The "Freequency response correction" is a correction spectrum with 1/3rd octave resolution that is specific for the currently
selected transducer. It is stored with the results and can therefore be turned on and off after the measurement is finished.
This is typically done in postprocessing software.