Efficient Coding of Natural Sounds

Mike Lewicki

Abstract

The auditory system encodes sound by decomposing the amplitude signal arriving at the ear into multiple frequency bands whose center frequencies and bandwidths are exponentially related to the distance from the stapes. This particular organization is thought to result from the adaptation of cochlear mechanisms to the auditory environment. Theories of sensory coding based on the idea of maximizing information transmission and eliminating statistical redundancy from the raw sensory signal and have been successful in explaining several properties of neural responses in the visual system including the population of receptive fields in visual cortex, but it is not known whether these theories can also explain sensory coding in the auditory system. In this talk, I will show how efficient coding of natural sounds yields filtering properties similar to those of the auditory nerves, and can resemble both wavelet and Fourier transforms depending on the class of sounds for which the derived sensory code is optimized. These results provide evidence that the neural coding of auditory signals approaches an information theoretic optimum, and further support the hypothesis that efficient coding could provide a general principle of sensory coding.

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