Re: A question on Bekesy. (David Mountain )


Subject: Re: A question on Bekesy.
From:    David Mountain  <dcm@xxxxxxxx>
Date:    Sat, 20 Mar 2010 09:43:44 -0400
List-Archive:<http://lists.mcgill.ca/scripts/wa.exe?LIST=AUDITORY>

--0015174478f4132f2404823ba783 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable Over the years our group has dissected many cochleae and I can assure you that the endolymph has a viscosity very similar to water. On Fri, Mar 19, 2010 at 6:09 PM, reinifrosch@xxxxxxxx < reinifrosch@xxxxxxxx> wrote: > Harriet, > > Yes, the TM is generally described as gelatinous. Nevertheless, > I now think that the mentioned sentence from page 475 of Bekesy's > book does not refer to the TM. I have read all of that book a few > years ago, but unfortunately have forgotten many details. Today I > found a sentence on page 467: > > "If Reissner's membrane was removed and the material within the > cochlear duct was washed away, the elastic properties of the > tectorial membrane could be investigated [...]" > (Bekesy's Article 47, first published 1947 in JASA). > > Bekesy apparently thought that the "material within the cochlear > duct" has a large viscosity. On his page 469, it says: > > "The cochlear duct is bounded on the one side by the basilar membrane, > and on the other side its viscous contents are contained by the thin > Reissner's membrane." > (Article 39, first published in German in 1941; published in English > in JASA in 1948). > > Bekesy mentions that gelatinous mass also on his page 443: > > "When the gelatinous mass of the cochlear duct was removed from > the basilar membrane with a fine brush the traveling waves were observed > with a larger amplitude and less damping." > (Article 42, first published in German in 1942; published in English > in JASA in 1949; in that experiment, there was apparently no agar- > gelatin mixture, only dental cement). > > So the problem is still unsolved. Are we sure today that the > "material in the cochlear duct" has a viscosity close to that > of water? > > (I shall comment on Bekesy's BM stiffness measurements, > i.e., his Fig. 11-73, later.) > > Reinhart. > > ----Urspr=FCngliche Nachricht---- > Von: hjacobster@xxxxxxxx > Datum: 19.03.2010 20:29 > An: <reinifrosch@xxxxxxxx>, <AUDITORY@xxxxxxxx> > Betreff: Re: A question on B=E9k=E9sy. > > If I recall correctly from my studies with Dr. Tonndorf, that was how he > described the TM. It stuck with me all > these years. > > > > However, it is always possible that my memory may be a bit faulty on this= . > > > > ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ > > Harriet B. Jacobster, Au.D., CCC-A, FAAA > > Board Certified in Audiology > > hjacobster@xxxxxxxx > > ---------------------------------------------------------- > > Reinhart Frosch, > > Dr. phil. nat., > > r. PSI and ETH Zurich, > > Sommerhaldenstr. 5B, > > CH-5200 Brugg. > > Phone: 0041 56 441 77 72. > > Mobile: 0041 79 754 30 32. > > E-mail: reinifrosch@xxxxxxxx . > --=20 David C. Mountain, Ph.D. Professor of Biomedical Engineering Boston University 44 Cummington St. Boston, MA 02215 Email: dcm@xxxxxxxx Website: http://www.bu.edu/hrc/research/laboratories/auditory-biophysics/ Phone: (617) 353-4343 FAX: (617) 353-6766 Office: ERB 413 --0015174478f4132f2404823ba783 Content-Type: text/html; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable Over the years our group has dissected many cochleae and I can assure you t= hat the endolymph has a viscosity very similar to water.<br><br><div class= =3D"gmail_quote">On Fri, Mar 19, 2010 at 6:09 PM, <a href=3D"mailto:reinifr= osch@xxxxxxxx">reinifrosch@xxxxxxxx</a> <span dir=3D"ltr">&lt;<a href= =3D"mailto:reinifrosch@xxxxxxxx">reinifrosch@xxxxxxxx</a>&gt;</span> wr= ote:<br> <blockquote class=3D"gmail_quote" style=3D"margin:0 0 0 .8ex;border-left:1p= x #ccc solid;padding-left:1ex;">Harriet,<br> <br> Yes, the TM is generally described as gelatinous. Nevertheless,<br> I now think that the mentioned sentence from page 475 of Bekesy&#39;s<br> book does not refer to the TM. I have read all of that book a few<br> years ago, but unfortunately have forgotten many details. Today I<br> found a sentence on page 467:<br> <br> &quot;If Reissner&#39;s membrane was removed and the material within the<br= > cochlear duct was washed away, the elastic properties of the<br> tectorial membrane could be investigated [...]&quot;<br> (Bekesy&#39;s Article 47, first published 1947 in JASA).<br> <br> Bekesy apparently thought that the &quot;material within the cochlear<br> duct&quot; has a large viscosity. On his page 469, it says:<br> <br> &quot;The cochlear duct is bounded on the one side by the basilar membrane,= <br> and on the other side its viscous contents are contained by the thin<br> Reissner&#39;s membrane.&quot;<br> (Article 39, first published in German in 1941; published in English<br> in JASA in 1948).<br> <br> Bekesy mentions that gelatinous mass also on his page 443:<br> <br> &quot;When the gelatinous mass of the cochlear duct was removed from<br> the basilar membrane with a fine brush the traveling waves were observed<br= > with a larger amplitude and less damping.&quot;<br> (Article 42, first published in German in 1942; published in English<br> in JASA in 1949; in that experiment, there was apparently no agar-<br> gelatin mixture, only dental cement).<br> <br> So the problem is still unsolved. Are we sure today that the<br> &quot;material in the cochlear duct&quot; has a viscosity close to that<br> of water?<br> <br> (I shall comment on Bekesy&#39;s BM stiffness measurements,<br> i.e., his Fig. 11-73, later.)<br> <br> Reinhart.<br> <br> ----Urspr=FCngliche Nachricht----<br> Von: <a href=3D"mailto:hjacobster@xxxxxxxx">hjacobster@xxxxxxxx</a><br> Datum: 19.03.2010 20:29<br> An: &lt;<a href=3D"mailto:reinifrosch@xxxxxxxx">reinifrosch@xxxxxxxx</a= >&gt;, &lt;<a href=3D"mailto:AUDITORY@xxxxxxxx">AUDITORY@xxxxxxxx= L.CA</a>&gt;<br> Betreff: Re: A question on B=E9k=E9sy.<br> <br> If I recall correctly from my studies with Dr. Tonndorf, that was how he de= scribed the TM. =A0It stuck with me all<br> these years.<br> <br> <br> <br> However, it is always possible that my memory may be a bit faulty on this.<= br> <br> <br> <br> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~<br> <br> Harriet B. Jacobster, Au.D., CCC-A, FAAA<br> <br> Board Certified in Audiology<br> <br> <a href=3D"mailto:hjacobster@xxxxxxxx">hjacobster@xxxxxxxx</a><br> <br> ----------------------------------------------------------<br> <br> Reinhart Frosch,<br> <br> Dr. phil. nat.,<br> <br> r. PSI and ETH Zurich,<br> <br> Sommerhaldenstr. 5B,<br> <br> CH-5200 Brugg.<br> <br> Phone: 0041 56 441 77 72.<br> <br> Mobile: 0041 79 754 30 32.<br> <br> E-mail: <a href=3D"mailto:reinifrosch@xxxxxxxx">reinifrosch@xxxxxxxx</a= > .<br> </blockquote></div><br><br clear=3D"all"><br>-- <br><br>David C. Mountain, = Ph.D.<br>Professor of Biomedical Engineering<br><br>Boston University<br>44= Cummington St.<br>Boston, MA 02215<br><br>Email: =A0 <a href=3D"mailto:dcm= @xxxxxxxx">dcm@xxxxxxxx</a><br> Website: <a href=3D"http://www.bu.edu/hrc/research/laboratories/auditory-bi= ophysics/">http://www.bu.edu/hrc/research/laboratories/auditory-biophysics/= </a><br>Phone: =A0 (617) 353-4343<br>FAX: =A0 =A0 (617) 353-6766<br>Office:= =A0ERB 413<br> <br> --0015174478f4132f2404823ba783--


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