While many of the noise studies have looked at cause models of
frequency and amplitude, they haven't much addressed timbre, or
classes of sound. This adds another dimension to the issue, but one
that is nonetheless vital to a comprehensive overview. In other words,
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
On Mar 15, 2009, at 5:28 AM, Wil Hershberger wrote:
> I recorded Wilson's warblers in the area of Yuba pass, route 49,
> Sierra Ca., in 1995. The birds with territories near the highway,
> which was used by logging trucks, sang very loud songs compared to
> other males much farther from the road. These were personal
> observations from the gain level settings on the recorder and the over
> loading of the mic and unfortunately not based on actual SPL
> measurements. However, that would be a great place to test this
> hypothesis.
>
> Wil Hershberger
> Nature Images and Sounds, LLC
> Hedgesville, WV
> The Songs of Insects
> My Blog
>
> On Mar 14, 2009, at 9:10 PM, Bernie Krause wrote:
>
> > The experiments are "in the pipe" and on the way, Steve.
> >
> > Bernie
> >
> > On Mar 14, 2009, at 5:49 PM, Steve Pelikan wrote:
> >
> > > There's been a fair bit of work done on the effects of man-made
> > > noises on the singing of birds. Good evidence that some song birds
> > > shift the frequencies of their songs in the presence of background
> > > noise that interferes with usual frequencies and some good work
> > > showing that individual birds sing louder in the presence of a
> loud
> > > background noise. That sort of study ---loudness ---is very time
> > > consuming since to determine the loudness of several sounds
> > > simultaneously and at a distance is complicated. Finally, there's
> > > beginning to be some evidence that oscine's learning of songs
> can be
> > > influenced (via some sort of sensory masking) by other sounds in
> the
> > > environment and that this can lead to rapid adaptation of songs to
> > > settings with artificial noise.
> > >
> > > Most of the studies along these lines that I've seen have treated
> > > the ambient noise --- of necessity--- rather simplistically (long
> > > term statistics on amplitude, frequency) either sampled at the
> time
> > > that the birds are recorded or at least at the season and
> locations
> > > where the birds are recorded.
> > >
> > > Rob's suggestion that it would be interesting to look for
> effects of
> > > specific sounds (or of sounds with specific properties) is a good
> > > one. I don't know of any work along these lines. Please let me
> know
> > > if you do...
> > >
> > > It is often hard to get good spectrograms from ambient (eg
> binaural)
> > > recordings so some scheme that records a soundscape at the same
> time
> > > that "closeup/high gain" recordings of individual singers is made
> > > might be required. Or imagine a field with a grid of microphones
> > > spaced out in it and a (64+?) track recording! One could chart the
> > > movements of singers in the environment as well as their songs ---
> > > something I've always been interested in.
> > >
> > > The other problem I imagine is that a huge amount of data would be
> > > required in order to examine the effect of specific sounds on
> > > singing behaviour unless one were to concentrate on a sound that
> the
> > > experimenter introduces. Probably long-term recordings and some
> > > computer scanning process to isolate relevant samples.
> > >
> > > I can easily imagine writing the software and would be
> interested in
> > > people's ideas for the recording setup.
> > >
> > > More importantly, what do you think would be a good subject
> > > (Melospiza with different exposures to roadside noises based on
> > > distance from highways?) and location? But what specific
> > > (artificial) sounds to focus on? I haven't got a decent hypothesis
> > > to propose.
> > >
> > > All this is great fun to think about as it could well be part of
> the
> > > next generation of experiments, it seems.
> > >
> > > Cheers!
> > > Steve P
> > >
> > >
> > >
> >
> > Wild Sanctuary
> > POB 536
> > Glen Ellen, CA 95442
> > 707-996-6677
> > http://www.wildsanctuary.com
> >
> > Google Earth zooms: http://earth.wildsanctuary.com
> > SKYPE: biophony
> >
> >
> >
> >
>
>
>
>
Wild Sanctuary
POB 536
Glen Ellen, CA 95442
707-996-6677
http://www.wildsanctuary.com
Google Earth zooms: http://earth.wildsanctuary.com
SKYPE: biophony
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