--- In Dan Dugan <> wrote:
>
> > in some of our work, we found evidence that loudness of a particular
> > sound classified as noise didn't have nearly as pronounced an affect
> > as the way the noise was perceived (in our case, recorded). Where
> > amplitude of the noise had no effect on the biophony, a much softer,
> > but more complex class of sound, did. In my post yesterday, I
> > described that an F-16 jet flying over a caribou herd with
> > afterburners blazing had no aversion effect, but that the "noise" of
> > someone approaching the herd on snowshoes most definitely would.
>
> Bernie, this is what drives me crazy about those academic
> bioacousticians who want to reduce everything to dBA readings. So far
> as I'm concerned, absolute levels of nature sounds are pretty much
> meaningless. It's the nature of the sounds that counts.
>
> The challenge for those of us who want to influence the academics is
> to develop new types of measurements that reflect what's important.
Dan,
I think that we have to distinguish between studies that try to investigate the
mechanisms of the acoustic communication between individuals of the same
species (which I believe is what Travis is doing) and studies that deal with
aversion effects.
I fully agree that the aversion behavior of a caribou herd must be triggered by
the quality of the sounds, while the absolute sound level is almost irrelevant.
The animals just know that a continuous broad-band noise does not represent a
danger to them, while a soft crackling noise could represent a dangerous
predator approaching them. I guess that these mechanisms are not new to
academic researchers...
Raimund
"While a picture is worth a thousand words, a
sound is worth a thousand pictures." R. Murray Schafer via Bernie Krause
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