Abstract on SOAEs. ("reinifrosch@xxxxxxxx" )


Subject: Abstract on SOAEs.
From:    "reinifrosch@xxxxxxxx"  <reinifrosch@xxxxxxxx>
Date:    Fri, 26 Nov 2010 13:21:55 +0000
List-Archive:<http://lists.mcgill.ca/scripts/wa.exe?LIST=AUDITORY>

------=_Part_2045_20363327.1290777715349 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable Dear colleagues, The abstract included below was recently accepted for a poster presentation= by the organizers of an international conference to be held next summer. N= ow I decided to not attend that conference and therefore to withdraw the co= ntribution. I plan to submit a similar abstract for a later conference. The= main ideas of the described analysis are presented in Chapters 26 and 44 o= f my new book, "Introduction to Cochlear Waves", available via the publishe= r (www.vdf.ethz.ch) or also via amazon Germany (www.amazon.de).=20 =20 Cochlear Evanescent Liquid Sound-Pressure Waves Near Localized Oscillations= of the Basilar Membrane. Evanescent liquid sound-pressure waves (i.e., standing waves, of limited sp= atial extension, with variable pressure and liquid-particle velocity but ne= gligible density variation) play a fairly important role, e.g., in a part o= f the models for the origin of spontaneous oto-acoustic emissions (SOAEs). = The corresponding liquid sound-pressure function obeys the Laplace equation= . These waves can be studied with the help of resonators such as tuning for= ks or drinking glasses. The free-oscillation frequency reductions caused by= submerging the resonators in water amount to a semitone for tuning forks, = and to more than an octave for completely submerged drinking glasses. These= frequency reductions are shown to be mostly due to the kinetic energy of t= he evanescent waves generated by the resonators. A plausible liquid sound-p= ressure wave function near a localized oscillation of the basilar membrane = (BM) of a cochlear box model can be found, e.g., by superimposing the waves= generated by a miniaturized tuning-fork prong (prong radius 0.1 mm, prong = axis oriented in y-direction and located at z =3D 0, x =3D 9.99, 10.00, or = 10.01 mm), oscillating in z-direction; at time t =3D 0, the prong is moment= arily at rest and has, in the three mentioned cases, a "vertical" displacem= ent of -100 nm, +200 nm, and -100 nm. Analytic calculations of the lines of= constant liquid sound-pressure amplitude, of the BM shape at time t =3D 0,= and of the evanescent-wave streamlines (along which the liquid particles o= scillate linearly) are described. A typical free BM oscillation frequency r= atio (without-liquid / with-liquid) is shown to be 1.3, corresponding to ab= out 0.4 octave. If such a BM oscillation generates a single-frequency SOAE,= then the place of maximal oscillation amplitude is basal of the without-li= quid BM resonance place for that frequency by 0.4 octave distance, i.e., by= about 2 mm, so that the emission can be carried to the stapes by a "slow" = travelling liquid-surface wave.=20 =20 With best wishes, Reinhart. Reinhart Frosch, Dr. phil. nat., CH-5200 Brugg. reinifrosch@xxxxxxxx . ------=_Part_2045_20363327.1290777715349 Content-Type: text/html;charset="UTF-8" Content-Transfer-Encoding: quoted-printable <html><head><style type=3D'text/css'> <!-- div.bwmail { background-color:#ffffff; font-family: Trebuchet MS,Arial,Helv= etica, sans-serif; font-size: small; margin:0; padding:0;} div.bwmail p { margin:0; padding:0; } div.bwmail table { font-family: Trebuchet MS,Arial,Helvetica, sans-serif; f= ont-size: small; } div.bwmail li { margin:0; padding:0; } --> </style> </head><body><div class=3D'bwmail'><P><FONT size=3D2>Dear colleagues,</FONT= ></P> <P><FONT size=3D2>The abstract included below was recently accepted for a p= oster presentation by the organizers of an international conference to be h= eld next summer. Now I decided to not attend that conference and therefore = to withdraw the contribution. I plan to submit a similar abstract for a lat= er conference. The main ideas of the described analysis are presented in Ch= apters 26 and 44 of my new book, "Introduction to Cochlear Waves", availabl= e via the publisher (</FONT><A href=3D"http://www.vdf.ethz.ch"><FONT size= =3D2>www.vdf.ethz.ch</FONT></A><FONT size=3D2>) or also via amazon Germany = (</FONT><A href=3D"http://www.amazon.de"><FONT size=3D2>www.amazon.de</FONT= ></A><FONT size=3D2>). </FONT></P> <P><FONT size=3D2></FONT>&nbsp;</P> <P><FONT size=3D2>Cochlear Evanescent Liquid Sound-Pressure Waves Near Loca= lized Oscillations of the Basilar Membrane.</FONT></P> <P><FONT size=3D2>Evanescent liquid sound-pressure waves (i.e., standing wa= ves, of limited spatial extension, with variable pressure and liquid-partic= le velocity but negligible density variation) play a fairly important role,= e.g., in a part of the models for the origin of spontaneous oto-acoustic e= missions (SOAEs). The corresponding liquid sound-pressure function obeys th= e Laplace equation. These waves can be studied with the help of resonators = such as tuning forks or drinking glasses. The free-oscillation frequency re= ductions caused by submerging the resonators in water amount to a semitone = for tuning forks, and to more than an octave for completely submerged drink= ing glasses. These frequency reductions are shown to be mostly due to the k= inetic energy of the evanescent waves generated by the resonators. A plausi= ble liquid sound-pressure wave function near a localized oscillation of the= basilar membrane (BM) of a cochlear box model can be found, e.g., by super= imposing the waves generated by a miniaturized tuning-fork prong (prong rad= ius 0.1 mm, prong axis oriented in y-direction and located at z =3D 0, x = =3D 9.99, 10.00, or 10.01 mm), oscillating in z-direction; at time t =3D 0,= the prong is momentarily at rest and has, in the three mentioned cases, a = "vertical" displacement of -100 nm, +200 nm, and -100 nm. Analytic calculat= ions of the lines of constant liquid sound-pressure amplitude, of the BM sh= ape at time t =3D 0, and of the evanescent-wave streamlines (along which th= e liquid particles oscillate linearly) are described. A typical free BM osc= illation frequency ratio (without-liquid / with-liquid) is shown to be 1.3,= corresponding to about 0.4 octave. If such a BM oscillation generates a si= ngle-frequency SOAE, then the place of maximal oscillation amplitude is bas= al of the without-liquid BM resonance place for that frequency by 0.4 octav= e distance, i.e., by about 2 mm, so that the emission can be carried to the= stapes by a "slow" travelling liquid-surface wave. </FONT></P> <P><FONT size=3D2></FONT>&nbsp;</P> <P><FONT size=3D2>With best wishes,<BR>Reinhart.</FONT></P> <P><FONT size=3D2><BR>Reinhart Frosch,<BR>Dr. phil. nat.,<BR>CH-5200 Brugg.= <BR>reinifrosch@xxxxxxxx . </FONT></P></div></body></html> ------=_Part_2045_20363327.1290777715349--


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