download some sounds of cavitation from internet. i found quite a few videos are on youtube so you can download and save them as .mp3 files, (make sure no other sound is present other than the sound of the machine, so any narration or background noises should be removed from the sound files as this would effect the results and readings of the graph) then read into matlab and perform a fast fourier transform on them. please make sure you have the original videos as i will need to compare and explain what happened in the video to other experiments. sound of any cavitation is fine as long as you make it clear which graph is for which video. thank you.