Hello Dick and List,
This is my second attempt to send this posting.
In travelling surface waves in the cochlear channel, involving restoring forces 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 pressure and liquid-particle velocity but negligible liquid density variation; they would occur also in strictly incompressible liquids (in contrast to "ordinary" sound waves). There is a different category with negligible liquid density variation, namely the so-called evanescent waves. These are standing waves; they occur, e.g., in filled wine glasses tapped by spoons. In evanescent waves, the liquid particles move linearly back and forth.
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 treated. They are also discussed in two recent two-page proceedings papers [Canadian Acoustics, Vol. 38 No. 3 (2010), 62-63 and 88-89].
Dr. phil. nat.,
Datum: 14.01.2011 02:09
Betreff: Re: sound waves in water
I believe Tony is correct, but there are also
sound waves "on" water, which have a transverse
component, as in the water waves you mentioned.
This is more like the kind of wave you find at
the interface between fluid and membrane in the
I think that any kind of vibration that
propagates can be called sound; for a transverse
component to propagate, you need something to
provide a transverse restoring force. For waves
on water, gravity provides that; on the BM in the
cochlea, the BM stiffness provides it. In free
water with no boundaries nearby, probably you
just get compression waves.