I have been reading through the PAMGuard help files and was wondering over what frequency range does PAMGuard measure the background noise level in order to trigger a click detection? Does the measure of noise level come from the full frequency range of the incoming audio, or does it come from the pre-filter? For example if the user sets the pre-filter to a bandpass of say 20 kHz, would the noise level be calculated from ~20 kHz and above, or is the pre-filter just filtering the data stored in the click detection itself?