Re: pitch neurons

[Martin Braun <nombraun@xxxxxxxxxxxxxxx>]

Israel Nelken wrote:

> When you
> say 'pitch neuron', I understand that you are looking for a neuron that
> should respond to pitch irrespective of the underlying physical
> structure of the stimulus - missing fundamental or not, iterated ripple
> noise, high-pass filtered click trains, binaural or monaural, and so on
> and so forth.

Dennis Phillips wrote:

> Pitch percepts arise from a host of very diverse stimulus configurations.

Dear Eli, Dennis, and List,
I suggest we should never forget that this "host of very diverse stimulus
configurations" is a lab artefact. No ears or brains are in any way adapted
to "iterated ripple noise, or high-pass filtered click trains". They are not
even adapted to "pure tones". These things do not occur outside the lab.

Outside the lab all sound is broad-band noise with varying amounts of
periodic components. If these are strong enough, we hear pitch, otherwise we
don't.

The advantage of detecting a pitch is that it helps the animal to identify
and follow a sound source. In order to do this, the animal needs ONE pitch
detector, not several. More than one would only lead to a more diffuse
pitch.

It is obvious that complex sound with only unresolved harmonics produces a
pitch perception. But such sound is non-existent in a natural environment,
and this pitch percept is weaker and slower than that caused by natural
sound with resolved harmonics. Experiments with unnatural periodic sound are
useful to test the limits of certain systems, but they never justify the
conclusion that we have two or more pitch detectors. It would be more
plausible to say that, upon artificial periodic sound, non-pitch systems can
deliver information to the pitch system as a by-product.

Martin

-------------------------------------------
Martin Braun
Neuroscience of Music
S-671 95 Klässbol
Sweden
e-mail: nombraun@post.netlink.se
web site: http://hem.netlink.se/~sbe29751/home.htm
-------------------------------------------

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Stage 1 .......................... "Totally absurd stuff."
Stage 2 .......................... "Interesting, but queer."
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Stage 4 .......................... "I have always said this."
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