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Pendulum or plausible combination?
At 01:11 19.03.2004 -0500, Tony Miller wrote:
>...a commentary by Shihab Shamma:
>...a deep understanding of the mechanisms that give rise to the pitch
percept remains elusive.
Yes, as long as we do not abandon or correctly unite both theories.
>This state of affairs is now likely to change dramatically
>in favor of the place theories with the publication of results of
>intricately designed psychoacoustic experiments by Oxenham et al. (1)
>reported in this issue of PNAS. "
These and all other arguments, in particular those by Baumann, would be
completely consistent with cochlear spectral analysis and corresponding
tonotopy as basis of a second neural analysis acting together like
autocorrelation of the original signal.
>Correct tonotopic representation is necessary for complex pitch perception.
This is correct, in principle. I merely fear it might not be prudent to use
the word 'complex' because it could be mistaken in the sense of a
justification for the wrong idea that hearing can be understood by means of
terms like magnitude and phase belonging to complex Fourier transform.
>In this study,"transposed stimuli" were used to dissociate temporal from
I see this approach already implying the wrong conclusion that temporal
processing can be excluded as a main mechanism. Do not get me wrong, I
maintain my suggestion: Brain performs temporal processing based on
tonotopy. Nobody offered a convincing idea how neurons could perform signal
processing in a complex frequency domain. If tonotopy was the final result,
structure of midbrain could be much simpler.
Facing fierce emotional rejection, I have to reveal deeply rooted tacit
fallacies behind it.
Physicists wrongly imagine Fourier cosine transform (FCT) just a special
case of complex Fourier transform (FT). Meanwhile some of them admitted
that FCT in IR+ is a correct equally complete alternative to FT in IR.
Physiologists are, as a rule, less familiar with mathematics. They are not
aware of the fact that the FCT-based natural spectrogram delivers just the
same temporal fine structure as does cochlea. Be honest, everybody vaguely
imagines cochlea preserving fine structure of the signal. This is incorrect.
Steven Greenberg described the notorious debate on spectral vs. temporal
code about as follows: The pendulum has swung in favor of temporal models.
Don't all serious contribution to our debate and the wealth of all other
known facts confirm the possiblity I am suggesting? A combination of
real-valued CB-modified cochlear frequency analysis with subsequent
rectification and further tonotopic temporal neural analysis constitutes
the physiological correlates for pitch perception. Those who distrust the
Wiener-Chintchine theorem might take cepstral analysis a model how pitch
perception presumably works.