High frequency material (birds above 4kHz and bats, in general) is
much more likely to reveal point source than the lower frequency
elephants and whales. It's almost impossible to get direction with any
accuracy when elephants are rumbling around 15Hz or whales are
vocalizing even lower because of the long wave form. What is puzzling
about that idea is why/how whales and elephants localize these sounds
and are observed drawn to the vicinity of the low freq "singers" when
our tech doesn't do such a great job.
Bernie
On Dec 17, 2008, at 11:29 AM, werainey wrote:
> There's a substantial literature on 'passive acoustic localization',
> mostly as Bernie indicates
> from the marine mammal literature. Quite a bit of it emerges from
> long term placements of
> passive monitoring buoys. Mellinger's freeware program 'Ishmael' has
> code modules for
> analyzing source position from various configurations of hydrophones.
>
> For birds, folks associated with Cornell labs (and others) have
> deployed microphone arrays to
> monitor at smaller scales time and place of calls from territorial
> song birds. This also has
> worked for 2 or 3d flying bat localization. There are a number of
> 'one-off' studies, but more
> recently several groups have been using Raimund Specht's multi-
> microphone systems and
> signal capture/software software
>
>
> Some interesting wrinkles emerge in discussions of elephant calling
> in that they are described
> as relying on reflecting calls off low level atmospheric inversions
> to extend their
> communication range.
>
> Bill R.
> >
> > However, I believe Chris Clark, at Cornell, has done this in a
> marine
> > environment with a hydrophone array while monitoring Bowhead Whales.
> > His questions were how many were in the pod? and where were they
> > located in relationship to one another? With the tetrahedral
> array, I
> > think he got some good data, if I recall correctly. I don't know if
> > he's published, but I think so.
> >
> > Bernie
> >
> > On Dec 17, 2008, at 5:05 AM, Marc Myers wrote:
> >
> > > Hi Bernie
> > > Thanks for the prompt response.
> > > What gear have you used, what software are you using and are any
> of
> > > the results published?
> > > Marc
>
>
>
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