Problem getting data from an AudioSource.clip - frequency check always returns 5512

I'm trying to build a very rudimentary pitch contour from a voice sample, and as I don't need much accuracy the easiest way to do this seemed to be to check the fundamental frequency of the recording at some given interval, build an array containing the value of the F0 at each time, then draw that array as a graph to show the general trend of the speaker's pitch.
I'm trying to accomplish this with two functions: ParseAudioData takes an AudioClip and a float interval, which is the number of...

Problem getting data from an AudioSource.clip - frequency check always returns 5512