Anyone happen to know the frequency of (interior) blue grouse hooting? I
recall video taping them with a cheapo camera & stock mic. The bird was
strutting around on the ground, hooting occasionally. I remember thinking
how low the sound was. When I watched the tape later, it was a silent film!
The mic didn't even pick it up!
I've read that male spruce grouse call even lower than blues. I personally
haven't heard one. Maybe they can't be heard by humans?
Mark Phinney
on 10/30/03 8:37 PM, Rich Peet at wrote:
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
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