Fundamentally it required a single function – cross-correlation – to measure the similarity of two data samples (audio files in this case). And it turns out that Octave provides it in the box.

What Is Cross-Correlation? Cross-correlation is a measurement that tracks the movements of two or more sets of time series data relative to one another. It is used to compare multiple time series ...

W. F. Welsh, On the Reliability of Cross‐Correlation Function LagDeterminations in ActiveGalactic Nuclei, Publications of the Astronomical Society of the Pacific, Vol. 111, No. 765 (November 1999), pp ...