The SPL Meter displays a value based on the RMS level of the selected
input channel, offset to correspond to an SPL reading that is calibrated
against an external meter. Valid readings are not displayed until
SPL Calibration has been carried out,
the meter figures are red if the SPL reading has not been calibrated. If
clipping is occuring on the input (the soundcard input range is being exceeded)
the Clip indicator at the top right of
the display is lit.
The SPL reading is filtered to make it easier to read fluctuating values,
the filter is controlled by the SPL Update selector. For general use the
"Slow" setting is best, when measuring subwoofer levels with pink noise the
"Very Slow" setting should be used to average out the random fluctuations of
the subwoofer calibration signal.
The soundcard input channel which is measured is selected in the Soundcard settings. Setting the audio input is described in Getting Started.
The SPL reading may be calibrated against an external SPL meter by pressing the Calibrate SPL button. The text on the button is red if the meter has not been calibrated