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How the auditory system maps
temporal acoustic cues into spatial patterns
Shihab A. Shamma
University of Maryland
The perception of sound involves a complex array of attributes,
ranging from the sensation of timber and pitch, to the localization
and fusion of sound sources. Computational strategies proposed to
describe these phenomena have emphasized temporal features in the
representation of sound in the auditory system. This is in contrast
to visual processing where spatial features, such as edges, their
orientation and direction of motion selectivity, play a critical role
in defining an image. These divergent views of auditory and visual
processing have led to the conclusion that the underlying neural
networks must be quite different. However, if one adopts the tonotopic
axis of the cochlea as the spatial axis of the auditory system, one
finds a multitude of intricate spatio-temporal cues in the neural
response patterns distributed along the tonotopic axis of the
peripheral and central auditory system. These findings suggest a
unified computational framework, and hence shared neural network
architectures, for central auditory and visual
processing. Specifically, we shall demonstrate here how four
fundamental concepts in visual processing play an analogous role in
auditory processing and perception. These are: (1) Lateral inhibition
for extraction of the acoustic spectrum in the cochlear nucleus; (2)
Edge orientation and direction of motion sensitivity for spectral
analysis underlying timbre perception; (3) Coincidence detection (as
in figure/surround segregation and perception of bilateral symmetry)
for sound source-delineation based on common onsets and harmonic
relationships, and for complex pitch perception in general; (4)
stereopsis for binaural processing and localization.