--- In Rob Danielson <> wrote:
>
> At 3:48 PM +0000 3/13/09, Raimund Specht wrote:
> >--- In
> ><naturerecordists%40yahoogroups.com>=
com,
> >Rob Danielson <type@> wrote:
> >
> >> Hi Raimund--
> >> I'm still wondering what folks are proposing to sufficiently document
> >> the back ground sounds as they appear to be the primary variable in
> >> his study. If directional mics are needed to gain the 6-10dB of extra
> >> separation from other, ongoing HF sounds, perhaps Steve's idea of a 4
> >> channel recorder is a good route for Travis to pursue. I have been
> >> reading good things and hearing some impressive files generated with
> >> the Edirol R-4 Pro, but I think even the R-44 pre's have been
> >> upgraded since the initial release. Rob D.
> >>
> >
> >Hi Rob,
> >
> >I'm not sure whether it is required to record the background noise
> >simultaneously. I guess that the background noise is in most cases
> >more or less stationary so that it would be sufficient to take a
> >short sample before or after recording the individual bird songs. If
> >that was not sufficient, I think that one could still use a common
> >stereo recorder. Another strategy might be to use just a single
> >(calibrated) omnidirectional microphone for both. If the distance
> >between the microphone and the singing bird is not too long, the
> >spectrographic analysis of the bird song might still work reliably
> >enough.
> >
> >Regards,
> >Raimund
> >
>
> Hi Raimund--
>
> Isn't it true with most animals that background sounds are most
> distractive when changing in volume and/or pitch? I also wouldn't
> rule out low frequency impacts because stress can reduce the amount
> of singling, not just the song. I don't know if its the surroundings
> here in SW Wisconsin, but I often find/see Phoebe nests tucked into
> structures with lots of mass-- concrete silos, stone walls, just
> inside caves and brick buildings. In the examples that come to mind,
> the nests were positioned so that road sounds were partially abated.
> I would definitely opt for recordings that would allow me to study
> the background dynamics in sync.
>
> In the city at distance of a few blocks from roads the background
> levels might become reasonably steady above 100 Hz. In no locations
> are background sound levels consistent under 40 Hz because these
> sounds come from great distance. And, of course you'd want to be to
> track the dynamics of the background sounds that are masking the
> speech bandwidths of which there are many. I'd want a stereo
> recording because-- during and after the fact-- when I can tell where
> a sound is coming from, its identification is much more certain. I
> have little trouble localizing sounds at 80Hz with a capable stereo
> array, including binaural.
>
> The only trouble I have making clear sonograms out of recordings made
> with ambient rigs is when two or more callers are going at once. Its
> hit and miss on the location of the intruding caller(s) even with a
> shotgun. With two omni's in an ambient rig, you get spatial imaging
> and the ability to use either channel for sonograms. Rob D.
>
>
> --
>
>
Rob I think your idea of recording the background noise in sync with the bi=
rd song is an interesting concept. For the purposes of my study I will mos=
t likely be recording the ambient noise directly before and after the bird =
song is recorded in order to get a general idea of the overall noise level =
of the area. In the end I am hoping to determine that Phoebes alter their =
song, whether it is time of day, duration, frequency, etc. in response to u=
rban noise. I will be comparing Phoebes found in rural locations vs. those=
found in several urban parks. I think simultaneous recording would be the=
next step to take if I found an alteration in the song and I wanted to dis=
cover more about the response of the bird song to specific urban noises. I=
just wanted to thank you all again for getting involved and helping me thr=
ough some of the more technical aspects of my project. I am enjoying the b=
ack and forth of ideas as it is helping me to think of the nearly limitless=
directions I could pursue.
Travis
|