An integrative model of pitch perception of rapidly changing sounds.


Our auditory system has an extreme sensitivity for temporal and pitch features of
natural sounds. However, time and  pitch are not independent magnitudes for our brains. Rapidly changing sounds, such as chirps, flutters or vibratos evoke pitch percepts that depend on the time  course of the instantaneous frequency of the signal. The mechanisms underlying the pitch assignment for these kind of signals are still a matter of debate.
Pitch theories roughly group into two main domains: place-rate and  temporal autocorrelation theories. Place theories fail to predict the time dependence of the perceived pitch for rapidly changing sounds,  since identical excitation patterns in the auditory nerve could lead to different pitch percepts. Temporal coding of instantaneous frequency could be performed, in principle, by auditory nerve fibers, but autocorrelation models fail to predict some new results in the perception of asymmetrical vibratos.
We propose  a new mechanism of pitch perception for rapidly changing sounds that integrates information of the place-rate code and the temporal code, performing simple and neuron-like operations. We compare the predictions of our model with the results of a psychophysical experiement using asymmetrical vibratos.