3 ms·

Hz is revolutions per second, so RPM = Hz x 60.

• lifeformed 12y ago
  But is a single revolution equal to 1 Hz of audio? What if the blade made two click sounds in a single revolution. Wouldn't that double the pitch, compared to a blade that made a single click?
  • TheLoneWolfling 12y ago
    True. But most of the time the fundamental will be once per revolution.
  • arcticsilo 12y ago
    (Blog author here) If you check out the spectrograms you'll see that there are a lot of different frequencies in the audio. I wasn't sure if the most powerful frequency would be the true rotation rate, so that's why I wanted to have a separate method to check. However, as TheLoneWolfing mentioned, it turns out that the most powerful frequency is indeed once per revolution.