Subject: Re: sound waves in water From: "reinifrosch@xxxxxxxx" <reinifrosch@xxxxxxxx> Date: Fri, 14 Jan 2011 21:51:07 +0000 List-Archive:<http://lists.mcgill.ca/scripts/wa.exe?LIST=AUDITORY>------=_Part_4083_31811518.1295041867545 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable Hello Dick and List, This is my second attempt to send this posting. =20 In travelling surface waves in the cochlear channel, involving restoring fo= rces provided by the elastic basilar membrane, the liquid particles move on= closed elliptical trajectories. These waves are indeed similar to surface = waves propagating on the ocean. They involve periodically varying liquid p= ressure and liquid-particle velocity but negligible liquid density variatio= n; they would occur also in strictly incompressible liquids (in contrast t= o "ordinary" sound waves). There is a different category with negligible li= quid density variation, namely the so-called evanescent waves. These are st= anding waves; they occur, e.g., in filled wine glasses tapped by spoons. In= evanescent waves, the liquid particles move linearly back and forth.=20 A few months ago, I have published a book "Introduction to Cochlear Waves" = (available via www.amazon.de) in which the above-mentioned waves are treat= ed. They are also discussed in two recent two-page proceedings papers [Cana= dian Acoustics, Vol. 38 No. 3 (2010), 62-63 and 88-89]. Reinhart. Reinhart Frosch, Dr. phil. nat., CH-5200 Brugg. reinifrosch@xxxxxxxx . ----Urspr=C3=BCngliche Nachricht---- Von: DickLyon@xxxxxxxx Datum: 14.01.2011 02:09 An: <AUDITORY@xxxxxxxx> Betreff: Re: sound waves in water I believe Tony is correct, but there are also=20 sound waves "on" water, which have a transverse=20 component, as in the water waves you mentioned.=20 This is more like the kind of wave you find at=20 the interface between fluid and membrane in the=20 cochlea. I think that any kind of vibration that=20 propagates can be called sound; for a transverse=20 component to propagate, you need something to=20 provide a transverse restoring force. For waves=20 on water, gravity provides that; on the BM in the=20 cochlea, the BM stiffness provides it. In free=20 water with no boundaries nearby, probably you=20 just get compression waves. Dick ------=_Part_4083_31811518.1295041867545 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>Hello Dick and List,</= FONT></P> <P><FONT size=3D2>This is my second attempt to send this posting. &nbs= p; </FONT></P> <P><FONT size=3D2>In travelling surface waves in the cochlear channel, invo= lving restoring forces provided by the elastic basilar membrane, the liquid= particles move on closed elliptical trajectories. These waves are indeed s= imilar to surface waves propagating on the ocean. They involve periodically= varying liquid pressure and liquid-particle velocity but negligible = liquid density variation; they would occur also in strictly incompres= sible liquids (in contrast to "ordinary" sound waves). There is a different= category with negligible liquid density variation, namely the so-called ev= anescent waves. These are standing waves; they occur, e.g., in filled wine = glasses tapped by spoons. In evanescent waves, the liquid particles move li= nearly back and forth. </FONT></P> <P><FONT size=3D2>A few months ago, I have published a book "Introduction t= o Cochlear Waves" (available via </FONT><A href=3D"http://www.amazon.de"><F= ONT size=3D2>www.amazon.de</FONT></A><FONT size=3D2>) in which the ab= ove-mentioned waves are treated. They are also discussed in two recent two-= page proceedings papers [Canadian Acoustics, Vol. 38 No. 3 (2010), 62-63 an= d 88-89].</FONT></P> <P><FONT size=3D2>Reinhart.<BR><BR>Reinhart Frosch,<BR>Dr. phil. nat.,<BR>C= H-5200 Brugg.<BR>reinifrosch@xxxxxxxx .<BR><BR></FONT></P> <BLOCKQUOTE><FONT size=3D2>----Urspr=C3=BCngliche Nachricht----<BR>Von: Dic= kLyon@xxxxxxxx<BR>Datum: 14.01.2011 02:09<BR>An: <AUDITORY@xxxxxxxx= A><BR>Betreff: Re: sound waves in water<BR><BR>I believe Tony is correct= , but there are also <BR>sound waves "on" water, which have a transverse <B= R>component, as in the water waves you mentioned. <BR>This is more like the= kind of wave you find at <BR>the interface between fluid and membrane in t= he <BR>cochlea.<BR><BR>I think that any kind of vibration that <BR>propagat= es can be called sound; for a transverse <BR>component to propagate, you ne= ed something to <BR>provide a transverse restoring force. For waves <= BR>on water, gravity provides that; on the BM in the <BR>cochlea, the BM st= iffness provides it. In free <BR>water with no boundaries nearby, pro= bably you <BR>just get compression waves.<BR><BR>Dick</FONT></BLOCKQUOTE></= div></body></html> ------=_Part_4083_31811518.1295041867545--