From: "Graham M Smith" <>
> I know this a group more concerned with high quality sound recording -
> rather than using sound recording equipment as an ecological monitoring
> tool, but I suspect the expertise is here to help.
There are those of us that have other concerns. I, for instance, have
ongoing surveys of frog distributions documented by sound recording.
While we would like good recordings, any that we can recognize the calls
will do for that.
> Indeed any suggestions to run these surveys better would be appreciated.
> Ideally, I would like a recording tool that would run for three nights,
> unattended with the recording activated by the bat call.
This is possible with some MD recorders. My Portadisc, for instance has
a function where it will monitor the sound levels on the input and
record only when these are above a preset level. Combine that with it's
record ahead buffer and you would capture the calls, though maybe other
louder sounds as well. But, a Portadisc is way too expensive to set out
for unattended recording. It does have digital (real-time) outputs, I
use it's digital optical output to move recordings to my mac.
> If anyone can suggest a better place to ask, then I would be grateful. I
> tried the Batline mailing list to see how other bat ecologists were deal=
ing
> with this, but got no reply.
You could always see if you can sweet talk Cornell out of some of their
Autonomous Recording Units, those can be programmed in quite a few
ways and are designed for this sort of work:
http://www.birds.cornell.edu/brp/Popup.html
There are a few other pieces of equipment around. Look for frog loggers.
Though most of those can only do interval recording, not sound activated.
General purpose recorders are not the best solution. The MD format is
limited as to it's read speed, so even if you got a way to do it that
would slow the downloads. They are not hard disks.
A general thought, before generating such huge amounts of recordings
that will have to be gone through make sure you will have time to
analyze them. In quite a few scientific fields it's quicker and easier
to collect data than analyze it. Most Oceanography departments, for
instance, are years behind in sorting their trawl samples, and getting
farther behind all the time. A great many of those expensively gathered
samples will never be gone over. Only collect as much data as you can
realistically analyze. Be selective.
Note also, if you are listening to analyze that you can play the MD
itself to do that, it does not have to be on computer. And you won't
wear the MD disk out playing it, just lock the disk if worried. And the
MD is archival, will hold that recording longer than just about anything
else. If you want to analyze a call on the computer, just transfer that
call section, not the whole recording. That's the way I'd handle
something like this. I'd use my sony MD deck that's hooked to my
computer, with it's convenient wireless remote. Easy to grab any bit I
wanted to computer, and my expensive portable recorder is not getting
the extra use.
Walt
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