--- In "Steve Pelikan" <> wrot=
e:
>
> 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 frequen=
cies of their songs in the presence of background noise that interferes wit=
h usual frequencies and some good work showing that individual birds sing l=
ouder in the presence of a loud background noise. That sort of study ---lou=
dness ---is very time consuming since to determine the loudness of several=
sounds simultaneously and at a distance is complicated. Finally, there's b=
eginning to be some evidence that oscine's learning of songs can be influen=
ced (via some sort of sensory masking) by other sounds in the environment a=
nd that this can lead to rapid adaptation of songs to settings with artific=
ial noise.
>
> Most of the studies along these lines that I've seen have treated the amb=
ient noise --- of necessity--- rather simplistically (long term statistic=
s on amplitude, frequency) either sampled at the time that the birds are r=
ecorded or at least at the season and locations where the birds are recorde=
d.
>
> Rob's suggestion that it would be interesting to look for effects of spec=
ific 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) reco=
rdings so some scheme that records a soundscape at the same time that "clos=
eup/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 environme=
nt 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 requir=
ed in order to examine the effect of specific sounds on singing behaviour u=
nless 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 peo=
ple's ideas for the recording setup.
>
> More importantly, what do you think would be a good subject (Melospiza wi=
th 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
Hi Steve,
I agree that this sort of research is quite complicated. I therefore belie=
ve that it is probably impossible to sort out these more specific questions=
in the field. In the lab it would be possible to expose the singers to var=
ious kinds of noise under very controlled conditions.
For instance, most of the research made on song learning has also been done=
in the lab because it would have been impossible to cope with the associat=
ed complexities in the field.
One research project that has shown that individual birds sing louder in th=
e presence of background noise signals of different spectral shapes has als=
o been done in a lab here at Freie Universitaet Berlin:
http://www.scribd.com/doc/2406140/Brumm-NoiseDependent-Song-Amplitude-Regul=
ation
Regards,
Raimund
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