Recommend doing spectrograms before, during and after. We've found
that some species of birds quiet down while others try to maintain
their acoustic niche within the biophony by becoming louder or more
active...even when that niche is covered by pink or white noise.
Frogs, in particular, seem to lose their chorusing ability during
periods of random masking noise (anthrophony, in particular, from
whatever source). Because our ears tend to compensate for the noise
(i. e. attenuate the effect), we cannot tell exactly what's going on
when anthrophony in relation to biophony occurs. A real good
spectrogram analysis reveals a lot of what's happening. We have
plenty of examples in that regard.
Bernie Krause
>on 9/5/05 10:02 AM, Don Lloyd at wrote:
>
>> <snip>
>> I believe some critters take advantage of pink noise 'confusing the spa=
ce',
>> as you put it. Whilst recording in marshes, I've noticed frogs and red-=
wing
>> blackbirds (among others) piping up when a jet plane blankets the area =
in
>> pink noise, or when a diesel truck downshifts on a nearby hill. When th=
e jet
>> or truck fades away, the frog chorus has reached critical mass and cont=
inues
>> on its own for a while, only to eventually die down and await the next
>> protective, predator-disorienting pink blanket.
>>
>>
>> -- Don
>>
>>
>
>I too have noticed that birds will crank up the volume when confronted wit=
h
>loud & 'unnatural' sounds. A few years back I was tasked with doing bird
>surveys in a relatively inaccessible area, so we used a helicopter to get =
to
>the place. I figured I'd have to wait at least 10 minutes after the choppe=
r
>left to let the birds recover, before starting the survey. I was surprised
>to find that they merely sang LOUDER (or so it seemed). I only had to wait
>until the chopper noise had subsided so that I could hear. Whether the bir=
ds
>were taking advantage of pink noise, or whether they were trying to
>compensate for the interference is up for debate, but whatever the case,
>they were certainly not frightened or put off by the extraneous noise. The
>same behaviour was apparent every time we did the survey.
>
>Mark Phinney
>
>
>
>
>"Microphones are not ears,
>Loudspeakers are not birds,
>A listening room is not nature."
>Klas Strandberg
>Yahoo! Groups Links
>
>
>
>
--
Wild Sanctuary
P. O. Box 536
Glen Ellen, CA 95442
t. 707-996-6677
f. 707-996-0280
http://www.wildsanctuary.com
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