{"items": [{"author": "Eric", "source_link": "https://www.facebook.com/jefftk/posts/672211121402?comment_id=672282453452", "anchor": "fb-672282453452", "service": "fb", "text": "The 440Hz Vs 451Hz thing is because you are using 512 bins of of probably 20,000Hz resulting in a bin size of 39Hz. The soft ware is then doing interpolation to guess the exact value.  If you up the number of bins to at least 2048 you should get a much better idea of where the peaks are.", "timestamp": "1407972987"}]}