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Re: The climb of absolute pitch

Dear Matt,
Your reference to Cariani's research into temporal properties of hearing reminded me of another observation he had made concerning the substantial effect phase associated with the complex stimulus had on the statistics of the ISI with the peaks being less pronounced than for a pure tone. I am not sure if there has ever been much discussion about phase in this forum, and have always wondered as to how the rest of this illustrious group understands this result.
IMHO I do agree with you that a feedback must be taking place if for nothing else than to account for phase even for a pure tone stimulus, which is why implementing source location in binaural experiments is so difficult. Get rid of the phase and the problem becomes much easier.
Thanks for bringing this up now as it does explain, to me at least, why the BM oscillates in that peculiar way and contrary to all explanatory models that have been offered for review. Regards,
Randy Randhawa

On 12/3/2012 11:46 AM, Matt Flax wrote:
Hi Bob,

There are studies which suggest that place and pitch are far from synonymous.

Consider Zheng's research and the references therein clearly demonstrate pitch reorganisation in rodents :

Also Cariani's research into temporal properties of hearing, in papers from '96 to 2001 and more... suggest that in certain frequency ranges time codes dominate!

Further, the alive and dead Cochlea exhibits large frequency shifts at the same place w.r.t. each other ... consequently it could be assumed that the neural control (efferent control) is very important for tuning our peripheral hearing circuit ... in my opinion, temporal control is working in conjunction with place effects... hard to think of them operating in isolation.

In the hypothesised mixed mode cochlear amplifier, the degree of feedback is critical to the tuning properties of each Cochlear segment. http://adsabs.harvard.edu/abs/2011AIPC.1403..611F
In a dead mouse ear, with no feedback, there is roughly a .25 octave shift (from memory) w.r.t. a healthy ear.


On 12/02/2012 07:47 AM, Bob Masta wrote:
Can someone explain the supposed mechanism behind neural 
timing and pitch shift?   I don't understand what is being 
proposed.  As I undestand it, since pitch is encoded as 
*place* along the BM, the neurons respond with a firing 
rate that encodes *loudness* for their particular frequency 
place.  The firing rate does not encode the frequency of 
the sound itself.  

What am I missing here?

Best regards,

Bob Masta

On 1 Dec 2012 at 9:50, Pierre Divenyi wrote:

Hi Oded,

Your three-step reasoning makes sense but, indeed, it should be
experimentally verified. As to the age-related change of neural
oscillations, Art Wingfield believes that the brain "slows down" as we get
older. Such a slowing-down could also explain the upward AP shift because
our reference would shift downward. How this central effect squares with the
peripheral, BM-stiffening effect is unknown but, again, could be studied in
the lab.


On 12/1/12 5:17 AM, "Oded Ghitza" <oghitza@xxxxxx> wrote:

Hi Pierre,
If (1) you accept Julius's model of pitch perception, (2) interpret -- as he
did -- the central component of the model as a mechanism that adjusts f0 of
an internal harmonic sieve to the point where the MMSE between the sieve and
the input pattern is minimum, and (3) assume that such mechanism is realized
by a neuronal circuitry with oscillations ("rhythms") at the core (maybe
related to Langer, in the late 80's and in the context of pitch perception,
who measured "temporal rings" in chicks); then, a possible way to examine
the phenomenon (whether perceived pitch should go up or down, in
particular), is to look at how the frequency range of neuronal oscillations
change with age. 

Bob Masta
            D A Q A R T A
Data AcQuisition And Real-Time Analysis
Scope, Spectrum, Spectrogram, Signal Generator
    Science with your sound card!