I'm trying to find a way to track the speed of a spinning roulette ball in real time through audio analysis, i.e. have a computer report the speed of the spinning ball it hears through a microphone. Here is a video of a spinning ball: I've tried watching a real time spectrum analyser (FFT), but haven't found any dominant frequencies to focus on, and there was a lot of noise. It might be possible if I find a very specific range of bins to track but I haven't found any yet. Here is a snapshot of the frequency domain 20 seconds in. It doesn't change much except get slightly quieter overall as the spin goes on. Here is what the audio of one spin looks like in the time domain. My brain can see the trend of the ball's speed slowing, but tracking amplitude alone would not work with background noise like music or talking. Any ideas? My brain can perceive the ball slowing when I listen so it must be somehow possible to get a computer to recognize it.