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This is for a research project on meditation. A music-type person composed for me an audio for paced breathing, which consists of some undulating tones. I would like to convert it to a smooth function for data analysis, where I will compare the function to some laboratory measurements, like heart rate. Here is a link to the audio file: Here is my code.

audio = Audio[File["BPM 8.wav"]];
selectData = MovingAverage[selectData, 20020]; 
ListLinePlot[selectData, PlotRange -> All, AspectRatio -> 1/10]

Here is the result

If I increase the moving average window, it loses its features. If I decrease the window, the result obviously gets noisier. I can't seem to a get a smooth function that has the features of this very regular tone.

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    $\begingroup$ hmm...what features do you want to extract? volume? pitch? If you take an average of a sound wave, you'll have a lot of cancellation in each of the pitch components (imagine the average of a sine wave over a long time). If you want to represent the volume, maybe take the root mean square over a certain window, or the maximum value over a certain window? But first you've got to decide on the abstract features you want before implementing them! :) $\endgroup$
    – thorimur
    Commented Dec 2, 2022 at 2:56
  • $\begingroup$ I don't really care what feature I extract. I just want to correlate the audio with some laboratory measurements (HRV, if you've heard of that) in meditators. But anyway, after I posted the above question, I realized that I really need to take the absolute value of the data file. Your idea of the root mean squared is probably even better. So thanks for that! $\endgroup$
    – Chris
    Commented Dec 2, 2022 at 22:34

1 Answer 1

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I'd suggest looking at the Audio* functionality for maximum efficiency. I'd do something like:

a = Audio["/Users/carlogico/Downloads/BPM 8.wav"];

AudioPlot[a]
Spectrogram[a]

AudioLocalMeasurements[a, "RMSAmplitude", 
  PartitionGranularity -> {Quantity[0.2, "Seconds"], 
    Quantity[0.1, "Seconds"]}] // ListLinePlot

Some pages to look at:

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  • $\begingroup$ This looks like the answer I'm looking for. I will try to implement your suggestion in coming days, and if it works I'll remember to attribute the answer to you. thanks. $\endgroup$
    – Chris
    Commented Dec 7, 2022 at 16:56

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