Human discrimination and modeling of high-frequency complex tones shed light on the neural codes for pitch
Fig 1
Representation of complex tones in a simulated auditory nerve.
(A). Simulated responses of a population of high-spontaneous-rate auditory-nerve fibers [52] for five periods of a sine-phase HCT composed of harmonics 4–13 at a level of 50 dB SPL per component and an F0 of 280 Hz. The middle panel shows a “neurogram”, or a plot of instantaneous firing rate as a function of time and characteristic frequency. In the neurogram, color (from purple [low] to yellow [high]) indicates the instantaneous firing rate analogous to color indicating intensity in a spectrogram. The top and left panels show the temporal waveform and spectrum, respectively, of the acoustic stimulus. In the left panel, the yellow box highlights the frequency ranges used in the behavioral experiments. The bottom two panels and right panels show the responses of individual nerve fibers over time and the response profile averaged over time, respectively, of the simulated neural response. The bottom two panels show responses for auditory-nerve fibers tuned to component frequencies (4F0, purple; 12F0, blue) or tuned between component frequencies (5.5F0, pink; 9.5F0, maroon). (B). Same as A, except for an F0 of 1400 Hz.