The Basic click Classifier is the same as the click classifier in the IFAW RainbowClick software. The basic classifier is generally adequate for the classification of high frequency harbour porpoise clicks.
Clicks are classified according to any or all of 4 different tests. Each test has a check box to the left of its parameters which can be used to enable or disable particular tests. All enabled tests must be passed for a positive classification to result.
Test 1. Energy Band comparison
The summed acoustic energy in two frequency bands (Test band and Control
band) is compared. The energy in each band must lie in the ranges
indicated and the ratio between the energy in the test band must exceed
that in the control band by the specified number of decibels.
Test 2. Peak Frequency position
The peak frequency must lie within a certain range. The search for the
peak frequency need not cover the entire spectrum - for instance, if low
frequency noise is always present, it will make more sense to start the
search at a higher frequency as shown in the example, where the search
is between 20kHz and 250kHz, and the peak frequency must lie in the
range 100kHz to 150kHz.
Test 3. Peak frequency width
Sets limits on the width of the spectral peak. The width is defined as
the minimum amount of spectrum required to sum up to the specified
percentage of the total click energy.
Test 4. Mean frequency
Sets limits on the mean frequency of the click energy within the
specified frequency band.
Test 5. Click length
Sets limits on the length of the click in milliseconds. The length is
defined as the minimum length of the data required to sum up to the
specified percentage of the total click energy.
Acoustic Alarm
Allows user to select the alarm associated with this click type. The alarms shown in the drop-down list are the ones previously defined in the Acoustic Alarm Settings window. The user is also able to specify a maximum amount of elapsed time between detections, to minimize alarming on spurious clicks and focus on specific inter-click intervals. The alarm will not sound on a click detection if the elapsed time since the previous click detection is greater than this number.
The 'Species Defaults' button allows the user to use stored standard settings for beaked whale and harbour porpoise classifiers.
Next: Advanced Click Classification