Introduction to Calibration

What is Calibration?

Calibration used to establish the sound pressure level of a sound recording.

Why Calibrate?

For some analyses this can be very important, and for some it is irrelevant. This depends, in part, on the purpose of the analysis. It also depends on the output parameter (and associated algorithm). Some outputs, such sound pressure level, are affected linearly by calibration - meaning that a change in the calibration offset results in a change of the same amount in the output. Some outputs, such as normalised autocorrelation function, are unaffected by calibration. Some outputs, such as psychoacoustical parameters, are derived from non-linear algorithms, and so do not have a simple relationship with calibration offset, making calibration very important.

Calibration Methods

The calibration method of PsySound3 is set in Preferences (in the File menu) - and changes to this should be made prior to analysis.

With Files

This calibration method asks for a calibration file, the sound pressure level of which is known. We recommend that this file have a duration of at least 10 s. The file might be a recording of a microphone calibrator, but could be a recording of anything that you know the equivalent sound pressure level of which was recorded with the same gain structure as the file(s) being analysed.

Without Files

This calibration method allows you to set the sound pressure level of the files being analysed in various ways based on measurement of the content in those files, or by using a simple gain offset relative to the program's default gain.

Set Full-scale Level

This setting allows you to state what the full scale level of the recording medium is (for a square wave). Having done this, the calibration part of the GUI is bypassed.

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