i figure i'll put it in pdb and poke at it to verify it
recording_fft = np.fft.rfft(recording)
# now take fft with np.fft.rfft
# then select only upper portion of 1 + bandwidth equal to period_length
# note: am guessing that period_in_recording = recording_bufsize / rfft_idx
# so, solving for rfft_idx
# rfft_idx = recording_bufsize / period_in_recording
# and, if right, that would be the index in the rfft output of the
period's peak
# so further data on it would be to the right, at higher frequencies
import pdb; pdb.set_trace()
fft_subregion = recording_fft[int(recording_bufsize / period_length)]
