Full-Name: Tilak Ratnanather
Newsgroups: bit.listserv.deaf-l
Date:         Wed, 2 Sep 1992 09:55:56 EDT
From:         "Tilak Ratnanather" <tratnana@EUREKA-GOLD.WBME.JHU.EDU>
Subject: Re: tongue shape
X-To:         DEAF-L%SIUCVMB.BitNet@pucc.PRINCETON.EDU

>	Tongue shape has been constructed from the speech signal alone
> in my case by the modelling of the vocal tract as a dynamic tube. By doing
> that, you can extract the tube resonances, or formant frequencies and thus
> with a little luck produce a tongue shape. Some use the signal to calculate
> area functions along the vocal tract to calculate the displacement of the
> tongue from the semi-rigid roof of the mouth and tract. In my case I am using
> an easier method which applies to vowels only.i.e. using an empirical
> relationship to describe displacement of thetongue at different points from
 the
> roof of the tract (although it assumes that at the start of the tract and the
> end (i.e. tongue root and tip) remain stationary (oops)). Well, I
> did say that it applied to vowels only, for now.

> 	We did consider using a new model in order to produce a 3D display of
> the tract in real time (just as a bent acoustic tube displayed in 3D), but can
> think of no use for such a prototype at the moment. Feedback we have received
> here suggests that a 3D model would not be as easily interpreted for speech
> therapy, although it MIGHT be of use for teaching purposes (?). We might
> therefore go a different direction altogether, like modelling the basilar
> membrane within the human ear to see what 'makes it tick' more properly. This
> could have deaf applications in the future. However I don't know much about
> that strand at the moment. Any ideas?

Martin:

I shall have to use DEAF-L to get to you. I sent mail earlier this
morning to you but it bounced back at the NSFNET-RELAY gateway. I will
send you the email address of the Hopkins expert when I get thru.

Now, you might like to look at the work of Christy Ludlow of NIH Voice
and Speech Pathology Section of NIDCD at Bethesda. He came over here
to give a seminar last week but I am afraid I missed it but I'll ask
the clinical guys here. Are you interested in mechanical modelling of
the vocal tract: if so you would have to consider a huge budget or joining
me on the brain drain :-)

I refereed a paper on the mechanics of the cochlea a couple of months ago
in which some work on the acoustics of elastic tubes were referred to. So
you might like to look at the work by Capper & Guelke of University of Cape
Town South Africa - see for instance ACUSTICA. I believe they drew a analogy
between the macromechanics of the cochlea and the dynamics of the vocal tract.

Finally, you say that you were thinking of modelling the basilar membrane to
find out what makes it tick. As a 'rookie' researcher in the micro-mechanics
of the cochlea who moved from theoretical and computational fluid dynamics,
I have to say that unless we understand the mechanics of the outer hair cells,
we wont know what makes the basilar membrane tick. Which is precisely why I
am working with one of the world's foremost experts on OHCs here at Hopkins.

To digress here, have you read the book 'Tuva or bust' by Ralph Leighton in
which Richard (Dick) Feynmann's last journey was covered in hilarious detail.
Feynmann, as some of the DEAF-L guys know, was a Nobel Laureate in Physics
and was known for his brilliant and lucid expository of physics. One side of
Dick emerged thru his two 'autobiographical' books: "Surely you're joking Mr
Feynmann" and "What do you care what others think about you?" (that is a very
appropriate attitude for many of us DEAF-L guys). Anyway, in 'Tuva or bust'
Dick discoverd that Tuvans (Tuva was part of the former Soviet empire amd may
be found next to Outer Mongolia and has the unique distinction of having its
capital city containg no vowels in its spelling: Kyzyl) were capable of
 producing
TWO tones  at the same time in throat singing!!!

Tilak Ratnanather
Dept of Otolaryngology -- Head & Neck Surgery
The Johns Hopkins University School of Medicine, Baltimore, MD, USA.
E-mail: tratnana@eureka-gold.wbme.jhu.edu