Summary:  How can I find something in the forest using the sound it
makes?  I want to get the exact position quickly.

Restrictions:  I have access to good microphones, wireless
tranmitters, GPS, laptop computers, and electricity.  I will be in a
fixed position.  The animal may be anywhere in my vicinity.  I have
limited time and limited money.

I want to be able to find an animal in a defined area of the forest. 
The animal makes loud noises.  Can I use the sounds to locate the
animal?  Specifically, is there a way I can triangulate a position
using microphones, a PC and a topographic map or GPS or both?  I need
an economical way to do this, with off-the-shelf software and tools. 
I own or can obtain a variety of microphones, GPS equipment, and
computers.

---

Clarification of Question by 15b-ga on 22 Aug 2006 04:43 PDT

I'm in a hurry.  I have some computer skills, but no programming experience.

---

Request for Question Clarification by denco-ga on 22 Aug 2006 13:04 PDT

Howdy 15b-ga,

Do you have access to additional people?

If you do, then 2, and better yet, 3 people with directional microphones,
means of communications with the lead person (you), the map and GPS unit
should do the job.  On the noise of the animal the three people at fixed
and mapped (GPS) positions use the directional microphones to locate the
bearing from which the sound is the loudest.

Then it is just a matter of transcribing those headings to the map and
then using the GPS coordinates to locate the animal.  If the animal is
mobile, then a fourth person should be used to find the animal, under
the direction of the lead person.

More technical, and presumably more "expensive, solutions exist.

"Locating far-field impulsive sound sources in air by triangulation."
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=11831786&dopt=Abstract

"A sound-triangulation method for counting Barred Owls."
http://elibrary.unm.edu/sora/Wilson/v076n03/p0292-p0294.pdf#search=%22sound%20triangulation%22

Does the above answer your question?  Thanks!

Looking Forward, denco-ga - Google Answers Researcher

Someone who knows better may quickly shoot this suggestion down, but
it seems to me that with well spaced, sensitive microphones hooked to
a computer with the right software, it should be possible to use
triangulation based on the relative loudness of the microphones'
reception of the animals sounds, i.e., without persons handling
directional mikes.

Try to envisage on a map of the area:  a series of concentric circles
around each of the GPS located mikes, representing the level of the
sound  - loudest near the mikes, barely audible for the mikes at the
outermost (largest) circle.  The computer would compare the sound
levels from the mikes and on its image of the map calculate the point
that satisfied the distance from each mike.

Maybe I have a layman's too great expectations about how well the
mikes' reception levels can be calibrated to indicate distance, but I
like the theory.

Of course, any wind is going to upset any triangulation based on an
audio system, so you'll also need a wind direction and speed device
plugged into the computer  - with a little calculation of its
information plugged into the software.

Having now read Denco's links, especially the first one, I guess that
if the animal were so helpful as to make short sharp noices  -
breaking branches or the like -  that the software could identify, it
could compare the difference in time that each mike reports and do the
triangulation calculation based on this information.

Kind of takes the fun and human element out of hunting ...  :-)

What kind of wireless transmitters do you have access to?  Does any of
your GPS equipment operate on battery power without PC assistance?  Do
you have sound editing software, or any means of digitally recording
sound?  If your wireless transmitters can send a number of audio
channels to a single PC, then there should be a simple solution.

A GPS device really won't help you that much as anything you plant it
on will remain stationary, and you could just as easily plot its
location on a map.