Beat Frequency

The beat frequency is equal to the absolute value of the difference in frequency of the two waves. Compute the actual beat frequency at each pixel, instead of just the fluctuation variance. This will entail using the Fast Fourier Transform, and choosing the frequency that is dominant at each pixel.

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Reference:

• http://hyperphysics.phy-astr.gsu.edu/hbase/Sound/beat.html
• http://cdn.cs50.net/2016/fall/seminars/automated_analysis_music/automated_analysis_music.pdf
• https://github.com/quinngroup/cilia-cbf