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Correlator Manual

Discussion of the correlation method

When the Avisoft-CORRELATOR is being used one should always keep in mind that the implemented correlation algorithm can fail to recognize complex spectrogram structures that could easily recognized by a human.

For this reason the correlation method is suited for the following kinds of spectrograms only:
  • The spectrograms should contain only a single syllable. If there is more than one syllable, the correlator would recognize similarities only if the distances between the syllables (and the temporal structure) were exactly matched.
  • The spectrograms should be generated using small FFT lengths or (and) small frame sizes in order to reduce the frequency resolution. High frequency resolutions tend to provide lower correlation coefficients in case there was a slight frequency deviation between otherwise visually very similar spectrograms.
Similarities between more complex spectrograms can be better quantified by using a multi-parametric approach (for instance the Automatic Parameter Measurements tool of the SASLab Pro software).

Avisoft Bioacoustics last modified on 15 October 2019