Speech and Chaos

William Calvin wcalvin at stein.u.washington.edu
Sat Jan 30 18:41:15 EST 1993


erwin at trwacs.fp.trw.com (Harry Erwin) writes:


>I'm exploring the possibility that speech may be a Pecora-Carroll process
>that synchronizes two perturbed quasi-periodic processes, one serving to
>select the utterance (at the deep grammar level) and the other serving to
>track the utterance.

>A Pecora-Carroll process is used to synchronize chaotic processes. The
>dynamics of the chaotic process are decomposed into two components, one
>transmitted between the two chaotic processes and the other duplicated at
>the individual chaotic processes. It is necessary and sufficient for
>synchronization that the lyapunov exponents for the variables in the 
>local components be negative. (This means that the variables in the 
>transmitted component must contain all periodic and chaotic variables
>in the dynamics.) The originators of this concept are Lou Pecora and Tom
>Carroll at NRL. Their papers have appeared in a number of IEEE journals.

>Steve Barry suggests some questions:
>1. Has there been anything yet done localizing deep grammar processing,
>and is the region the same for speech and hearing?
>2. In studies of shadow speech, what are the limits to the time delay
>between hearing the utterance and shadowing it? How about a paraphrase (or
>simultaneous translation) of the utterance?

>If speech is a P-C process, the driven process in the listener should have
>negative conditional lyapunov exponents. This could be explored using
>methods similar to those of Walt Freeman.

>It would be interesting to put together a dynamic, multi-level model of
>speech and hearing to see if a test model compatible with a quasi-periodic
>implementation is feasible.

>Cheers,
>-- 
>Harry Erwin
>Internet: erwin at trwacs.fp.trw.com

Good set of questions.  Nothing localizes "deep grammar" very well, but we
can say something about neural sequencing specializations that seem common
to both listening and production of speech; see the article in Behavioral
and Brain Science 1983 by George Ojemann on using electrical stimulation
of the cortex of awake epileptics during surgery, testing language and
related functions.  George and I are writing a new popular book to replace
INSIDE THE BRAIN (1980, now out of print) but it won't be out until 1994;
my book THE CEREBRAL SYMPHONY has some of this in it.
	On the more detailed level of coupling chaotic processes that
might correspond to some of the bits and pieces
 (phonemes and words and phrases), I've been thinking some about
sequencing strange attractors.
	Re shadowing speech, don't know the latencies.  But there is some
fascinating folklore on simultaneous translators, e.g., one school in
Belgium that teaches its students to knit while translating, thus
producing a background rhythmic carrier?
    William H. Calvin   WCalvin at U.Washington.edu
    University of Washington  NJ-15
    Seattle, Washington 98195 FAX:1-206-720-1989



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