Possible reconstruction of auditory signals by the central nervous system (CNS)

Tuned auditory neurons and behavioral sensitivity to the envelopes of neuronal responses rather than to phase‐locked discharge patterns [W. M. Siebert, Proc. IEEE 58, 723–730 (1970)] suggest that the CNS receives a spectrogram‐like representation of acoustic stimuli. How much information about the original input signal u(t) is preserved in such a representation? The spectrogram is the convolution of the signal's time‐frequency energy density function eu(t,f) with that of the filter which is used to construct the spectrogram [M. H. Ackroyd, J. Acoust. Soc. Am. 50, 1229–1231 (1971)]. By using two‐dimensional deconvolution, eu(t,f) can be obtained from the spectrogram. The signal's auto‐ambiguity function Xu(τ,φ) is the two‐dimensional Fourier transform of eu(t,f), and u(t)exp(jλ) can be obtained from Xu(τ,φ), where λ is an arbitrary constant [W. M. Siebert, MIT, Q. Prog. Rep., 90–94(1958)]. If the spectrogram model is valid, these observations imply that the CNS can, in principle, completely reconstruct the...