Jeff Lucas, an ornithologist at Purdue, has found that some birds
actually frequency shift signals during the processing of audio
input...particular those of like species. I'm thinking that one of the
reasons they do this is because since some, like the Black-Capped
Chickadee, Lucas' study sample, the birds need to find a way to have
their respective vox fit into frequency niches. Since they can't
easily either learn a new song/call, they just process it differently.
That may be an answer, along with the fact that migrating birds in
temperate regions, vocalize in what appears to us, given the recording
and analysis tech we've been using, to be a cacophony, but to the
birds, is a lovely, well-defined biophony.
Bernie
On Dec 20, 2008, at 6:41 AM, Curt Olson wrote:
> Bernie, would you be willing to elaborate on this?
>
> We know about differing frequency response characteristics. Skull
> structure, outer ear size, shape and placement will all certainly have
> their effect. So will brain power, channeled by inbred priorities and
> experience.
>
> What other factors would you point out?
>
> Curt Olson
>
> Bernie Krause wrote:
>
> > ...and don't forget that critters hear and process sound very
> > differently than we do.
> >
> > Bernie
> >
> > On Dec 19, 2008, at 12:29 PM, Marc Myers wrote:
> >
> >> The area depends on how far the calls can be heard. If one can say
> >> that the farthest call was at 300 meters, One has to say that's the
> >> limit. Topography, of course, effects everything but my guess is
> >> human ears will be more reliable than technology in terms of
> >> distinguishing the primary sources.
>
>
>
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