At 10:20 AM +0000 3/12/09, Raimund Specht wrote:
>--- In
><naturerecordists%40yahoogroups.com>=
m,
>Rob Danielson <> wrote:
>
>> I like the suggestion of tying to also make a record of the stimuli
>> that _could be_ triggering behaviors-- not relying on dB meters etc
>> which most of the studies seem to do,.. Moving the understandings
>> forward might require some new techniques-- especially outside of
>> labs as Travis seems committed to.
>>
>> Using multiple channels and somehow placing mics so they obtain the
>> aural perspective of the birds might be more necessary in loud
>> settings, but using a rig in both loud and quiet settings that is
>> optimized to record ambience accurately might provide a more
>> measurable sense of relative levels, sound source tonalities and
>> space/directionality compared to using "close-up" measure/arrays.
>> We've all noticed, many times, how parabolas and shotguns alter the
>> impression of the background sounds. Of course, one can make mental
>> note these discrepancies in the field, but the info does not get
>> embedded in the scientific record like it could with a rig designed
>> for ambience. The dynamics of directional mics are quite dependent
>> upon aiming and the direction that the critter happens to be calling.
>> If I was trying to determine how loud a caller was calling to
>> overcome other (background) sounds, I'd much rather have an ambient
>> recording to work with.
>>
>> One of the questions in my mind is whether very good binaural gear
>> might be a good way to go. I can almost always detect qualities using
>> good headphones that analysis software and great monitor speakers are
>> blind to. Rob D.
>
>Hi Rob,
>
>Such kind of research on sound propagation and the influence of
>noise has already been done:
>
><http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=3D2216701>http:=
//www.pubmedcentral.nih.gov/articlerender.fcgi?artid=3D2216701
><http://www.scielo.br/scielo.php?pid=3DS0001-37652004000200011&script=3Dsc=
i_arttext>http://www.scielo.br/scielo.php?pid=3DS0001-37652004000200011&scr=
ipt=3Dsci_arttext
>
>I believe that simple binaural or stereo techniques, which are being
>used by amateur recordists are not appropriate for this kind of
>research. Instead one has to design the experimental setup very
>carefully in order to get meaningful and repeatable results, which
>is essential in a scientific study.
>
>Close-up recordings are in any case required for measuring the
>alterations of the individual animal vocalizations. The equipment
>for this task must be as simple as possible and the inherent noise
>level of the recording equipment is not important here. Instead, one
>should take care that the recorded sounds are not affected by
>unwanted environmental influences such as reverberation or other
>disturbing sounds. These effects are a much more relevant than the
>minor influence of the microphone or preamplifier noise levels.
>
>Regards,
>Raimund
>
Hi Raimund-
This is one of your specialities. I'm hoping to participate in the
equipment design questions in terms of what one can expect from gear
if trying to understand perception, bird, human, etc! :-) My
apologies if I'm off-target.
Of course, one would opt a good binaural rig, like the Neumann KU-100
or one of the better, lower-cost options using DPA4060's or 4053's.
These rigs are sophisticated and capable of producing very "accurate"
tonalities with more than sufficient separation for analysis even in
loud settings. Should one of these rigs prove incapable, I would be
even more suspicious of the foreground/background imagining I'd
obtain with a directional mic and mono recording. I'm assuming that
Travis needs good imaging of the "background" too. Am I off-course
about this?
I'm sure that we agree that location reverberations and other subtle
cues play very important roles in actual communications. Seems that
capturing these as best as possible for comparing urban/rural
behaviors would be beneficial, not undesirable.
It may be that I have more trust in the abilities of rigs designed to
represent acoustic spaces. I find they can tell me lot of things
about the settings and all of the sounds contained. The pubmedcentra
study you point to seems to have used playback to synthesize the
communication conditions. I feel Travis could be charting new
territory in attempting to understand animal responses in specific
environments where the settings _are_ the test variables. I'd rely
on a stationary binaural rig(s?) with long duration recordings to
generate the necessary control and repeatability factors. (I couldn't
locate the methodology and technology used in the other study you
referenced.)
If one is trying to use recordings to understand behavior, I would
think it would help enormously to establish "accurate" spatial
imaging along with calls that exhibit more than sufficient
figure-ground separation to evaluate with software. (I placed
"accurate" in quotes because I feel that all micing systems are
approximations with differing strengths and weaknesses.) Rob D
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