Hello Curious,
Look at the following link to see how a very simple mechanism converts sound
frequency to physical location.

http://hyperphysics.phy-astr.gsu.edu/hbase/sound/place.html


Clay S. Turner


"Curious" <curious11112001@yahoo.com> wrote in message
news:34a4f456.0408291118.7ad93137@posting.google.com...
> Nerves can fire up to 1 KHz max. At pitches above 1 KHz our cochlea
> makes-up for this by firing different lines of neurons at succesive
> cycles.
>
>
> http://www.cns.nyu.edu/~msl/courses/0022/lecturenotes/pitch/pitch.html
>
> "Volley Principle: The volley principle reconciles the fact that the
> cochlear microphonic mimics the sound pressure waves with the
> implausibility of the temporal code. Wever suggested that while one
> neuron alone could not carry the temporal code for a 20,000 Hz tone,
> 20 neurons, with staggered firing rates, could. Each neuron would
> respond on average to every 20th cycle of the pure tone, and the
> pooled neural responses would jointly contain the information that a
> 20,000 hz tone was being presented."
>
> "Phase Locking is an empirical observation that supports the volley
> principle.  When 8th nerve neurons fire action potentials, they tend
> to respond at times corresponding to a peak in the sound pressure
> waveform, i.e., when the basilar membrane moves up. The result of this
> is that there are a bunch of neurons firing near the peak of each and
> every cycle of a pure tone. No individual neuron can respond to every
> cycle of a sound signal, so there must be different neurons firing on
> successive cycles. Nonetheless, when they do respond they tend to fire
> together."
>
>
> Is it possible design an "parallel Hz" scheme similar to that of the
> cochlea?
>
> This is what I meant by "parallel Hz".

Jerry Avins <jya@ieee.org> wrote in message news:<41323f39$0$19715$61fed72c@news.rcn.com>...

> Using a poorly understood system as the basis of any but the most casual
> of analogies qualifies as arm waving in my book.

"There is a fine line between having solved a problem, and never have 
understood it"                             Paraphrase over Piet Hein.

Rune

Jerry Avins wrote:
> Curious wrote:

>> Nerves can fire up to 1 KHz max. At pitches above 1 KHz our cochlea
>> makes-up for this by firing different lines of neurons at succesive
>> cycles.

>> http://www.cns.nyu.edu/~msl/courses/0022/lecturenotes/pitch/pitch.html

>> "Volley Principle: The volley principle reconciles the fact that the
>> cochlear microphonic mimics the sound pressure waves with the
>> implausibility of the temporal code. Wever suggested that while one
>> neuron alone could not carry the temporal code for a 20,000 Hz tone,
>> 20 neurons, with staggered firing rates, could. Each neuron would
>> respond on average to every 20th cycle of the pure tone, and the
>> pooled neural responses would jointly contain the information that a
>> 20,000 hz tone was being presented."

>> "Phase Locking is an empirical observation that supports the volley
>> principle.  When 8th nerve neurons fire action potentials, they tend
>> to respond at times corresponding to a peak in the sound pressure
>> waveform, i.e., when the basilar membrane moves up. The result of this
>> is that there are a bunch of neurons firing near the peak of each and
>> every cycle of a pure tone. No individual neuron can respond to every
>> cycle of a sound signal, so there must be different neurons firing on
>> successive cycles. Nonetheless, when they do respond they tend to fire
>> together."

>> Is it possible design an "parallel Hz" scheme similar to that of the
>> cochlea?

>> This is what I meant by "parallel Hz".

Well, it is parallel in the sense that parallel nerves bring
the signals for different frequency ranges to the brain.

> Some structure has to receive impulses from all the neurons and sort
> them out. The transmission may be accomplished in parallel, but the
> analysis needs to look at everything, even if in a hierarchical way.

> The description above is a bit simplistic. Signals of different pitch
> arise in different parts of the cochlea, so the particular axon that
> carries a signal encodes its pitch at least in part.

> Using a poorly understood system as the basis of any but the most casual
> of analogies qualifies as arm waving in my book.

I agree.

The frequency information is not decoded that way at all.
To the extent that it is used at all, phase information is
processed as described.

Much of the location of sources of sound is done by small timing
differences in the arrival time of the sound to each ear, and
the frequency spectrum of those timing differences.
(It is very difficult to locate the source of a pure sine
wave because of the way it works.)

As far as musical sounds go, the stories that I know about
indicate the the ear/brain system is fairly insensitive to
phase.    It is rare for an audio system to avoid a 180
degree phase shift (polarity reversal), and it seems to be
mostly inaudible.

-- glen

Curious wrote:

> Nerves can fire up to 1 KHz max. At pitches above 1 KHz our cochlea
> makes-up for this by firing different lines of neurons at succesive
> cycles. 
> 
> 
> http://www.cns.nyu.edu/~msl/courses/0022/lecturenotes/pitch/pitch.html
> 
> "Volley Principle: The volley principle reconciles the fact that the
> cochlear microphonic mimics the sound pressure waves with the
> implausibility of the temporal code. Wever suggested that while one
> neuron alone could not carry the temporal code for a 20,000 Hz tone,
> 20 neurons, with staggered firing rates, could. Each neuron would
> respond on average to every 20th cycle of the pure tone, and the
> pooled neural responses would jointly contain the information that a
> 20,000 hz tone was being presented."
> 
> "Phase Locking is an empirical observation that supports the volley
> principle.  When 8th nerve neurons fire action potentials, they tend
> to respond at times corresponding to a peak in the sound pressure
> waveform, i.e., when the basilar membrane moves up. The result of this
> is that there are a bunch of neurons firing near the peak of each and
> every cycle of a pure tone. No individual neuron can respond to every
> cycle of a sound signal, so there must be different neurons firing on
> successive cycles. Nonetheless, when they do respond they tend to fire
> together."
> 
> 
> Is it possible design an "parallel Hz" scheme similar to that of the
> cochlea?
> 
> This is what I meant by "parallel Hz".

Some structure has to receive impulses from all the neurons and sort
them out. The transmission may be accomplished in parallel, but the
analysis needs to look at everything, even if in a hierarchical way.

The description above is a bit simplistic. Signals of different pitch
arise in different parts of the cochlea, so the particular axon that
carries a signal encodes its pitch at least in part.

Using a poorly understood system as the basis of any but the most casual
of analogies qualifies as arm waving in my book.

Jerry
-- 
Engineering is the art of making what you want from things you can get.
�����������������������������������������������������������������������

Curious wrote:

> Nerves can fire up to 1 KHz max. At pitches above 1 KHz our cochlea
> makes-up for this by firing different lines of neurons at succesive
> cycles. 
> 
> 
> http://www.cns.nyu.edu/~msl/courses/0022/lecturenotes/pitch/pitch.html
> 
> "Volley Principle: The volley principle reconciles the fact that the
> cochlear microphonic mimics the sound pressure waves with the
> implausibility of the temporal code. Wever suggested that while one
> neuron alone could not carry the temporal code for a 20,000 Hz tone,
> 20 neurons, with staggered firing rates, could. Each neuron would
> respond on average to every 20th cycle of the pure tone, and the
> pooled neural responses would jointly contain the information that a
> 20,000 hz tone was being presented."
> 
> "Phase Locking is an empirical observation that supports the volley
> principle.  When 8th nerve neurons fire action potentials, they tend
> to respond at times corresponding to a peak in the sound pressure
> waveform, i.e., when the basilar membrane moves up. The result of this
> is that there are a bunch of neurons firing near the peak of each and
> every cycle of a pure tone. No individual neuron can respond to every
> cycle of a sound signal, so there must be different neurons firing on
> successive cycles. Nonetheless, when they do respond they tend to fire
> together."
> 
> 
> Is it possible design an "parallel Hz" scheme similar to that of the
> cochlea?
> 
> This is what I meant by "parallel Hz".

It's what everyone else in the world means by "parallel processing", 
which in a digital signal processor (it's a DSP group, remember?) 
requires the use of "parallel bits".

-- 

Tim Wescott
Wescott Design Services
http://www.wescottdesign.com

Curious wrote:

> Nerves can fire up to 1 KHz max. At pitches above 1 KHz our cochlea
> makes-up for this by firing different lines of neurons at succesive
> cycles. 
> 

You're missing the point here - the frequency information has already 
been deteremined at this point - the firing rate is just an indication 
of the intensity at a particular place (frequency) on the cochlea. 
(Hint: think of the cochlea as a spectrum analyser.)

Paul

Nerves can fire up to 1 KHz max. At pitches above 1 KHz our cochlea
makes-up for this by firing different lines of neurons at succesive
cycles. 


http://www.cns.nyu.edu/~msl/courses/0022/lecturenotes/pitch/pitch.html

"Volley Principle: The volley principle reconciles the fact that the
cochlear microphonic mimics the sound pressure waves with the
implausibility of the temporal code. Wever suggested that while one
neuron alone could not carry the temporal code for a 20,000 Hz tone,
20 neurons, with staggered firing rates, could. Each neuron would
respond on average to every 20th cycle of the pure tone, and the
pooled neural responses would jointly contain the information that a
20,000 hz tone was being presented."

"Phase Locking is an empirical observation that supports the volley
principle.  When 8th nerve neurons fire action potentials, they tend
to respond at times corresponding to a peak in the sound pressure
waveform, i.e., when the basilar membrane moves up. The result of this
is that there are a bunch of neurons firing near the peak of each and
every cycle of a pure tone. No individual neuron can respond to every
cycle of a sound signal, so there must be different neurons firing on
successive cycles. Nonetheless, when they do respond they tend to fire
together."


Is it possible design an "parallel Hz" scheme similar to that of the
cochlea?

This is what I meant by "parallel Hz".