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.