detection can be made. This blanking-time is useful to avoid detecting echoes from a click or to
prevent detecting a large number of clicks if an animal is buzzing near the recorder.
4.1.2
Snippet extractor
For each detection, an entry is added to the detection log and a snippet of wideband sound
surrounding the detection time is saved. The snippet starts and ends a user-selectable time before
and after the detection (user parameters:
pre-trigger
and
post-trigger
). Evidently, saving longer
snippets per detection means that the memory is used up more rapidly so this feature allows the
user to trade-off the amount of context that is saved for each detection against the total recording
time. It is important to note that the snippet is taken from the whitened sound and so is high-pass
filtered.
4.1.3
User parameters
The user parameters can be set by clicking the ‘Configure’ button in the Detector section.
Threshold
: The level in dB that the power-in-band must exceed the ambient noise level by for a
detection to take place. A value of 12 dB will have a high detection rate but will produce many false
positives. A value of 20 dB will detect only strong transients that are well above the ambient noise
floor.
Integration Time
: Set this to the approximate duration of the clicks of interest. For most delphinids
you would use a short averaging time, e.g., 70 µs, while for beaked whales, porpoises and NBHF
delphinids, an averaging time of 150-300 µs would be appropriate. If you are interested in detecting
any toothed whale click, you can either go with a long averaging time (which will reduce the SNR of