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Re: propagation speed of the traveling wave

Dear List,

In my earlier answer (April 9, 2005, 13:20 h)
to Mark Rossi there are wrong numbers.

The mentioned figure of R. Patuzzi
("The Cochlea", page 211) is conistent
with the following values:

Water depths: h = 0.1, 1, 10, and 100 mm.
Stiffness E = 10^3 kg / (m^2 s^2).
Surface mass M = 1 kg / m^2.

Also, the cochlea is a double channel.
There is liquid on both sides of the
elastic "surface layer". That can be
accounted for by setting, in Patuzzi's
formula, the density to d = 2000 kg / m^3.

Consequence: At the base of the cochlea,
the long-wave model with its frequency-
independent propagation velocity is concluded,
via Patuzzi's formula and de Boers stiffness
(in his "The Cochlea" article), to be valid
for an even smaller range of frequencies,
namely for frequences much lower than 3.1 kHz.

Reinhart Frosch,
CH-5200 Brugg.

>-- Original-Nachricht --
>Date:         Fri, 8 Apr 2005 12:21:19 +0200
>Reply-To: "Rossi Mark (PA-ATMO1/EES21) *" <Mark.Rossi@xxxxxxxxxxxx>
>From: "Rossi Mark (PA-ATMO1/EES21) *" <Mark.Rossi@xxxxxxxxxxxx>
>Subject:      propagation speed of the traveling wave
>To: AUDITORY@xxxxxxxxxxxxxxx