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    Re: Noisy Sea Surface
    From: Rodney Myrvaagnes
    Date: 2003 Nov 15, 16:41 -0500

    On Sat, 15 Nov 2003 20:36:57 +0000, George Huxtable wrote:
    >That is: they are certainly individual clicks and not at all drawn-out
    >"scrapes". They are heard from below decks, the sound being transmitted
    >through the water and the hull, and not (or at least, very attenuated) from
    >on deck. I have heard many clicks per second, but these seem to be from
    >multiple sources, from all around the hull, not just from one or two
    >clickers, clicking madly from one place.
    This sounds like the same thing I heard in San Diego.
    Sound indeed is attenuated greatly as it passes through a surface
    between media of hugely different density. Think of how little the
    water surface would move for even a strong signal. I don't think the
    songs of Humpack whales are ever heard in the air. If they can be, I
    must have seen a lot of mute whales.
    The one exception I have experienced must have resulted from kilowatts
    into a hydrophone. When a US submarine is about to surface, it
    announces this in a stentorian but disembodied voice. It is unnerving,
    particularly because there is nothing you can do to stay out  of the
    way, since you don't know exactly where it will emerge.
    Rodney Myrvaagnes                       J36 Gjo/a
    A Great White dorsal fin, close enough alongside that the tail fin was outside peripheral vision

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