Fig. 3.

FFT of recordings from a fresh-frozen cadaver head in response to analogue dyads consisting of component frequencies of approximately F1 = 110 Hz and F2 = 220 Hz. Amplitudes of these primary frequencies are shown in each panel in blue and red text for F1 and F2, respectively. A distortion product at F2-F1 = 110 Hz is observed with an amplitude, indicated in orange text, that differs between (A) F1 and F2 superimposed, presented to the same electrode, B) F1 and F2 interleaved, presented to the same electrodes, and C) F1 and F2 interleaved and presented separately to adjacent electrodes