MATLAB: FFT- sound pressure (db) vs time (s)

fft frequency amplitude sound acoustic

I have sound data as SPL vs time for a structure fracturing. I would like to perform FFT to determine the frequencies most evident during fracture.
please could someone advise how to perform this? or where to start?

Best Answer

First, I would convert the decibel SPL values in decibels to the original amplitude values:
amplitude = 10.^(SPL/20);
Then use the fft (link) function. Specifically note the code between the first (top) two plot images.
I am not certain if the frequency content changes significantly during your recording, and if that is what you are interested in. If it is, consider using the spectrogram (link) function if it would be more appropriate to what you want from your data.
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