There's been a fair bit of work done on the effects of man-made noises on t=
he singing of birds. Good evidence that some song birds shift the frequenci=
es of their songs in the presence of background noise that interferes with =
usual frequencies and some good work showing that individual birds sing lou=
der in the presence of a loud background noise. That sort of study ---loudn=
ess ---is very time consuming since to determine the loudness of several s=
ounds simultaneously and at a distance is complicated. Finally, there's beg=
inning to be some evidence that oscine's learning of songs can be influence=
d (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 artificia=
l noise.
Most of the studies along these lines that I've seen have treated the ambie=
nt noise --- of necessity--- rather simplistically (long term statistics =
on amplitude, frequency) either sampled at the time that the birds are rec=
orded 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 specif=
ic sounds (or of sounds with specific properties) is a good one. I don't kn=
ow 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) record=
ings so some scheme that records a soundscape at the same time that "closeu=
p/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+?) t=
rack 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 unl=
ess one were to concentrate on a sound that the experimenter introduces. Pr=
obably long-term recordings and some computer scanning process to isolate r=
elevant samples.
I can easily imagine writing the software and would be interested in peopl=
e'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?) a=
nd 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 g=
eneration of experiments, it seems.
Cheers!
Steve P
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