Jon Reisenbuechler wrote:
> Nature Recordists,
>
> Thank you for your responses, I look forward to hearing more. I am tryin=
g to better understand the cost/equipment commitment that will be needed to=
start recording animals (emphasis on bird chorus) for scientific research =
and educational purposes. As some of you probably know, birds are often st=
udied in their habitats using a 10 minute point count where a researcher re=
cords all species heard or seen from a central point. A listening radius c=
an cover 300 meters in good conditions. My primary goal is to make a fairl=
y accurate audio document of these point counts, another goal is to record =
individual species song dialects within the region.
>
> So what have I learned and what new questions have come up?
>
> The Recorder
> 1) MiniDisc recorders, mostly commercial products ranging from 150 to
$800. Record in ATRAC format which is designed around how humans
percieve sound. Sound quality that is not detected by us may be lost.
While this format is ok for learning and study it may not work so well
for scientific callback surveys since the species may hear the difference.
The top end HHb Portadisc, like I use, lists for $1500. Some have found
sources as cheap as $900.
At the risk of another round of ATRAC bashing, let's just say that the
worries about ATRAC being not recognized, or losing part of the sound,
etc. etc. are unfounded. It's probably the most common form of callback
recorder out there now. Works beautifully.
I've spent many years recording with Minidisc for scientific purposes.
No problems whatsoever that relate to minidisc, except that a walkman MD
is tiny, which is not a problem now that I use a Portadisc. Sonograms
are just fine, animals respond fine, scientists are very happy with my
recordings. Including this scientist.
Yes, there are those with no extended experience with the format who
keep saying otherwise. But people like myself who use it on a very
frequent basis say it works just fine, including science.
In some ways minidisc exceeds CD quality. It uses a bit shifting system
and 24 bit processing which is all stuff left out of the audio CD specs
which are a fixed 16bit format.
Cornell is not to be trusted in this regard, their stuff on equipment
still has up the sonogram of digital clipping that they have tried to
pass off as ATRAC damage for as long as I've been aware of minidisc. A
classical error of someone who is trained in analog recording moving
into digital recording. Fooled me for a long time until I tried to
duplicate it. Have to drive the Portadisc at least 6dB above clipping
level to duplicate that sonogram.
> 2) Marantz PMD690 Stereo PC Card recorder a professional model
recommended to me by Stith Recording (they provide some of Cornell Unv
equipment). Priced around $1300. Records onto PC cards in a variety of
formats including cd quality .wav.
This will tether you to a computer. Unless you are willing to invest in
a lot of expensive PC cards. It's a bit of a unknown in actual field use.
> I still have to investigate this area, especially along the lines of
media space/cost/reuse, connectors, battery usage.
I doubt you can do better than a Portadisc for the cost vs capability vs
sound quality in a true field recorder. Media is cheap and stores the
recordings for archival time periods. Can be reused, though I don't, I
keep all originals. The Portadisc will get close to 4 hours recording
out of 8 2000mah NIMH AA batteries. Somewhat less if providing phantom
power. Has a whole raft of connectors and recording bells and whistles.
And is human sized and built like a tank.
> The Mic
> Here is where it gets fun. The mic you use depends on what you want
to do.
> 1) to record a single species a directional mic is used. This may be
a short or long range "shotgun mic" for closer distances (??? meters) or
a mic with a parabolic reflector for those long distance recordings (
??? meters)
Let's say a optimistic guess for a high end shotgun setup of 100 meters.
My own experience has been that 50 meters can be pushing it. Distance
is primarily limited by self noise for both mic and preamp.
Parabolics it's much farther. I've recorded barking treefrogs from a
mile away good enough to be part of the survey record. It will pick up
things that are too faint to pick up by ear. But, note, it's a narrow
field, not the same thing to picking up 360 degrees to 300meters. You
would have to learn to pan to pick up all directions. This is true for
any mic with long reach. In fact for any mic you are likely to use
except a mono omni for a small circle.
> 2) to record a chorus an omnidirectional mic is used. This collects
sound from almost all directions in a fairly consistant fashion. I was
reccommended that a Sennheiser MKH20 would be ideal.
Actually I prefer to use organized mic setups rather than a single bare
mic. The MKH20 is a very good mic, but your chorus needs to be fairly close=
.
> I have the impression that stereo mics are better for both
situations. Is there a stereo omnidirectional mic?
There are stereo setups that use omnidirectional mics. You can use
spaced omnis, or omni's in a SASS, like the SASS/MKH-20 that Lang and I
have. You can even make up a MS setup with a omni mid, though it's not
considered very valuable. But a single omni mic does not get you stereo,
that's mono.
Stereo recording is better for survey recording as you can pick out the
individual callers much easier than you can from a mono recording. This
is particularly true of fainter calls mixed with louder stuff. It does
not get you more reach, in fact the common stereo mic setups are short
reach systems. But I do survey recording exclusively in stereo, and wish
my earlier mono ones were stereo too.
The idea of recording calls in stereo is fairly new to many nature
recordists. A great many still record mono. If recording a single
individual and you are going to filter out the ambiance it probably does
not matter.
> How sensitive are omnidirectional mics, will they pick up most sounds
within a 50m radius, how about 100m? Can an omnidirectional mic be used
with a parabolic reflector to record single species?
I think 50m would be pushing it a lot. Really loud callers will be
picked up from greater distance, but not the quieter stuff. In fact for
really quiet callers 50' might be pushing it.
Actual sensitivity varies, and is a combination of actual sensitivity,
mic noise, pre noise, and pre gain.
> Some Other Stuff
> 1) wind shields to prevent the noise a breeze makes as it blows over
your mircophone
See the response I posted to Doug today. Good protection is very
expensive if bought retail. It is a area where all sorts of homemade
things are tried, but it pays to understand the capability of the pro
windscreens first. What they design is for people who must get the
recording regardless of conditions.
> 2) good connector cables ensure that sound quality is maintained from
the mic to the recorder
Unless making really long runs, nature recording does not have a big
problem. Our locations don't tend to be highly electrically noisy.
I use Canare Star Quad cable with Neutric weatherproof XLR connectors. I
make my own cables. Almost everything I have uses balanced cables. The
cables I make are serious overkill for nature recording.
> 3) headphones to monitor the recording (ie see what you are
recording). Recorder needs to support this feature
Rather crucial. You should opt for high quality headphones, even out in
the field. You need even the faint stuff well defined. These should be
of the closed variety to prevent your mics from picking them up. I use
Sony MDR-V900's.
> 4) shock guards to minimize handling noise, less important for
ambient recording if a tripod is used.
Ideally built as part of your windscreen system. Needed even on tripods,
but less so.
Walt
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