At 7:39 PM -0500 12/18/08, Marc Myers wrote:
>My listening has been on the mainland but gibbons do elect some
>tough environments, probably because that's all we've left them.
>
>That said, I'm looking more for consistency of measurement and
>reducing errors than really accurate data analysis and the highest
>quality recording. Standard practice at present is to go to fixed
>point at dawn for two or three days in a row and then estimate the
>number of gibbons based on the calls. Clearly not good enough.
>
>A multichannel recording using a microphone array then later
>analyzing the recording in a lab occurred to me as well. I also
>thought of a variant, using multiple Zaxcom recorders. They can be
>locked to time code and then moved fairly far from one another.
>Geolocate each with a GPS and one would be good to go. The
>microphones father apart would be much easier to analyze and the
>number of points available to evaluate would be limited only to the
>number of recorders one had available in the field. But, any such a
>system that's based on triangulating based on the relative delays
>among the microphones would be hard to interpret in the field and
>will be replete with just the kinds of problems Bernie has
>elucidated. Also field surveys are usually budget operations.
Hi Marc--
You might be surprised what you are able to interpret with live
monitoring of the three signals with headphones panned hard left/hard
right/center. It might not be too hard to locate someone who could
make you an audio "plug-in" (similar to the real-time triangulation
processing in "Shot Spotter" as Bill suggested
http://www.wired.com/wired/archive/15.04/shotears.html) that
translates the timing differences from the mics into a real time map
graphic on your laptop. This "map" would be very useful for field
confirmation with 2-way radios. With recordings in hand, the most
precise location could be computed afterwards and might be important
for your science.
Can you give us an idea of the area you feel it would be practical to
cover and the relief of the landforms in the location if you know
this? Rob D.
>
>I'm thinking a little lower tech: Two listening stations with very
>directional microphones and head phones or maybe just a passive
>listening tube on a tripod, an attached GPS with electronic compass,
>some field notebooks and walkie-talkies. Gibbons start calling: Two
>observers locate the calls, coordinating with walkie-talkies. Using
>the compass and GPS location a bearing is taken on the call. The
>results can be analyzed with a map or GIS software. Thoughts?
>
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