Posted by: "Birding Africa (Callan Cohen)"
>
> I'm struggling to find software that will produce a clear sonogram for
> analysis and presenting bird calls. I appreciate that the clarity of the
> sonogram is affected by the quality of the recording, but it seems that e=
ven
> with very clear recordings, it is not so easy to produce a clear sonogram=
s
> without excessive "noise"?
>
> Are Kay Sono-graph sonograms (from a prohibitively expensive machine) tha=
t
> one sees in publications artificially clean?
When I worked with one there was no cleaning process. Though the analog
process may help a little. I don't remember the sonograms being all that
clean.
> Which programs can one use to get clear sonograms? I've tried Raven and
> syrinx-pc but I can't seem to get them even vaguely clear.
For the sonograms on my frog website I used Soundhack (mac software).
It contains a dynamics range filter that can be used to remove the
sounds below a set level. It's those quiet sounds that are most of the
noise. By careful choice of the cutoff level you can make the call
pretty clear.
http://wwknapp.home.mindspring.com/GAFrog.Toad.html
Other than putting names on no graphic editing was done on the sonograms
there. They are screen dumps. Getting sonograms out of Soundhack is not
straightforward as they are only in the program for entertainment (I got
that direct from the author when I asked)
Of course if applied too heavily you can end up removing some of the
call you are interested in.
For analysis you have to be careful doing this, though analysis does not
need all that clean a sonograms. For presentation it's helpful to make
the call clear.
The same filter is useful when cleaning up recordings for just listening
too. A good filter for removing artifacts from other filters.
http://www.soundhack.com/freeware.php
http://www.hitsquad.com/smm/programs/SoundHack/
For you windows folks this one may be able to do the same sort of thing.
http://www.soundslogical.com/products/wavewarp/wavewarp20.html
Ideally you get close enough to your caller that the call is well above
the background level. And you use a quality mic and recorder. Preferably
position the mic very high to minimize echoes and so on. Then the
sonogram is naturally clear.
Walt
|