Friends:
Walter Knapp wrote:
> Lately I have been thinking we are making a error in publishing
> recordings without man made noise.
I've been thinking about man made noise too. In many places it is a
significant part of an organism's environment. In addition to Walt's
point that our recordings should be honest about reflecting actual
levels of man-made noise (perhaps in the hope of influencing people and
policy), there's other good reasons to record around "civilization".
There's some recent work that shows birds sing louder when they're in
environments with man made noise, and that they shift the frequencies of
their vocalizations away from those masked by man made background noise.
The mechanisms for these changes have yet to be demonstrated, but
there's several good possibilities (masking during the learning process
make birds learn altered versions from their parents, or perhaps
selection for the better songs in a given environment with more
offspring in a generation learning from parents with more audible songs).
Since we know that our sounds affect animals, it seems a worthy project
to better understand the what and how it. That will require that we
record in the presence of noise. I'm trying to get used to it and not
curse (silently, under my breath) as a beautiful recording of a long
bout of song gets "ruined" by yet another Delta flight. I tell my self
it isn't "ruined" it's just the way it is; art is fine, but there's also
virtue in telling the (nearly objective) truth.
One bird related project that I'm in the middle of is made possible
because I (of necessity) recorded even in the presence of man made
noises. I'm re-examining my many old Northern Cardinal recordings to see
if there's any (statistical) evidence that loud sounds (passing cars,
airplanes) increase the chance that a bird will stop singing and/or
switch song types.
When I get a chance I also want to do a study to compare a quite with a
noise-filled setting. I'll look that the frequency with which cardinals
in the two setting sing different types of song. It'll justify my going
out of the way to record in a quiet place. And I'm betting it'll show a
difference.
Cheers!
Steve P
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