Adobe listserv agrees with Bernie as well and posted:
This is fascinating, Rich!
The clipping begins with the fifth "thump." You can see how the first
four are nicely rounded, and the subsequent ones become squared off
on one or both axes. The squared portion is not level because
electronics aren't very good at reproducing DC, even for a brief
moment! The clipping may have been in the mic pre; you might have
recorded this thinking that the level was fine while the low frequecy
of the thump saturated the electronics prior to the A/D converter.
So what is the frequency content of the thump? If you analyze the
length of one full cycle of the thump, or even copy it and loop paste
it numerous times to enable frequency analysis, you'll get answers in
the 40-50Hz range, which is still a pretty impressive noise for a
bird to actuate. If you do a frequency analysis of the whole file,
you'll find the most energy concentrated between 35-70 Hz.
I wouldn't call it infrasonic (unless you were positioned inside the
tree trunk!), but still quite amazing.
And I add:
To correct the possible proximity effect and possible clipping I post
for those that care the same bird recorded at about 50' with a Pine
Warbler stuck in the middle. A larger 1 meg download that sounds
about the same when heard by a speaker.
http://home.comcast.net/~richpeet/0298b.wav
Rich Peet
--- In "Rich Peet" <>
wrote:
> Thanks Bernie.
> Of course I am disappointed.
> I would have liked to have determined that I found a viable
recording
> package for recording infrasound for under $500.00.
>
> I wish I could find a source of accurate infrasound to use as a
check
> but all the freq generators I know of don't go there. I guess my
> next stop should be the zoo to visit elephants.
>
> Rich Peet
>
> --- In Wild Sanctuary
<>
> wrote:
> > In checking out the ruffed grouse signal, Rich, two things seem
to
> > happen depending on the software one uses. If I use a HAM
weighted
> > low pass filter setting, I certainly get a reading (probably
> > artifact) from the signal showing it almost down to zero. I doubt
> > it's THAT low. The wingbeats generate lots of pulsed air and,
> > depending on the habitat and input transducer, there can be
> > distortion and other acoustic anomalies introduced. If, on the
> other
> > hand, I look at the signal with the GWI system, I don't get much
if
> > any signal below 28.5Hz. That sounds more real to me and I would
> tend
> > to trust that analysis as being closer to what's actually
> happening,
> > if indeed, it's that low.
> >
> > Bernie Krause
> >
> > >64kb spectral display:
> > >http://home.comcast.net/~richpeet/grouse.jpg
> > >
> > >200 kb wave at:
> > >http://home.comcast.net/~richpeet/0298.wav
> > >
> > >Thanks, I really have these questions because I am not in the
audio
> > >business and am not an expert. I just do what I do.
> > >
> > >Rich Peet
> > >
> > >--- In Wild Sanctuary
> <>
> > >wrote:
> > >> Send a short .wav file, Rich, and I'll check it out, here, on
> the
> > >GWI
> > >> system. Sometimes recordings create an artifact that looks
like
> a
> > >> sub-harmonic but is really a "ghost" signal created by wierd
> sums
> > >and
> > >> differences.
> > >>
> > >> Bernie Krause
> > >>
> > >> Wild Sanctuary, Inc.
> > >> P. O. Box 536
> > >> Glen Ellen, CA 95442
> > >> 707-996-6677 tel
> > >> 707-996-0280 fax
> > >> http://www.wildsanctuary.com
> > >>
> > >> >They speak of calls of 18 hz. I asked and didn't get a
> response on
> > >> >if the grouse I recorded with a signature to 1/2 hz was
> accurate.
> > >> >I have now asked Adobe if the spectral display is correct.
> > >> >Maybe they (wcs.org) are speaking of voice calls at 18 hz
but
> if
> > >so I
> > >> >don't understand the body mechanics of that. The lowest I
have
> in
> > >> >voice recorded to date is the Great Gray Owl.
> > >> >
> > >> >Rich Peet
> > >> >
> > >> >
> > >> >--- In Doug Von Gausig
> > ><>
> > >> >wrote:
> > >> >> See http://wcs.org/7411/?art=3D110481374. Some dinosaur
folks
> are
> > >> >thinking
> > >> >> that the subsonic calls of the Cassowary may be very
> similar and
> > >> >> pleisiomorphic to the calls that Dinosaurs used to
> > >communicate...
> > >> >>
> > >> >> Doug
> > >> >> Doug Von Gausig
> > >> >> Clarkdale, Arizona, USA
> > >> >> Moderator
> > >> >> Nature Recordists e-mail group
> > >> >> http://groups.yahoo.com/group/naturerecordists
> > >> >
> > >> >
> > >> >
> > >> >To unsubscribe from this group, send an email to:
> > >> >
> > >> >
> > >> >
> > >> >
> > >> >Your use of Yahoo! Groups is subject to
> > >http://docs.yahoo.com/info/terms/
> > >>
> > >>
> > >> --
> > >
> > >
> > >
> > >To unsubscribe from this group, send an email to:
> > >
> > >
> > >
> > >
> > >Your use of Yahoo! Groups is subject to
> http://docs.yahoo.com/info/terms/
> >
> >
> > --
> > Wild Sanctuary, Inc.
> > P. O. Box 536
> > Glen Ellen, CA 95442
> > 707-996-6677 tel
> > 707-996-0280 fax
> > http://www.wildsanctuary.com
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