Abstract
Pitch perception is important for understanding speech prosody, music perception, recognizing tones in tonal languages, and perceiving speech in noisy environments. The two principal pitch perception theories consider the place of maximum neural excitation along the auditory nerve and the temporal pattern of the auditory neurons’ action potentials (spikes) as pitch cues. This paper describes a biophysical mechanism by which fine-structure temporal information can be extracted from the spikes generated at the auditory periphery. Deriving meaningful pitch-related information from spike times requires neural structures specialized in capturing synchronous or correlated activity from amongst neural events. The emergence of such pitch-processing neural mechanisms is described through a computational model of auditory processing. Simulation results show that a correlation-based, unsupervised, spike-based form of Hebbian learning can explain the development of neural structures required for recognizing the pitch of simple and complex tones, with or without the fundamental frequency. The temporal code is robust to variations in the spectral shape of the signal and thus can explain the phenomenon of pitch constancy.
Highlights
The existence of a pitch processing center or a group of specialized “pitch neurons” in the mammalian auditory system has been debated in recent years
Our auditory system has a sophisticated mechanism to process and perceive the neural information corresponding to pitch
Based on the known functions of the auditory system, we develop a computational model of pitch perception using a network of neurons with modifiable connections
Summary
The existence of a pitch processing center or a group of specialized “pitch neurons” in the mammalian auditory system has been debated in recent years. Through single unit recordings, Bendor and Wang [1] found a potential pitch center in the anterolateral border of primary auditory cortex in marmoset monkeys. These pitch neurons were characterized by sustained spiking in response to their preferred pitch, evoked by a pure tone or a harmonic complex. Through positron emission tomography (PET), Zatorre and Belin [2] found that areas in the lateral Heschl’s gyrus responded to the pitch of pure tones. Penagos et al [4] confirmed the sensitivity of the Heschl’s gyrus area to the pitch of harmonic complexes through fMRI investigations
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