We've got signal, but what the heck is it?
That's your mission. Analyze this bébé.
download the audio file 9.wav.gz
hints :
- No need to gunzip this file since baudline can automatically uncompress
files.
-
Setup baudline to be a Web Browser helper application as described in the
FAQ.
-
In the play deck, turn on the 60 Hz notch filter and set the digital gain boost
to +36dB.
What is it?
A baudline user wrote in:
I thought that I would note that your "mystery signal" is from a critter I
used to call by whistling. The originator is very good wrapped in bacon
and stuffed with wild rice and shallots.
Bacon?
Yes,
the mystery signal is indeed that of the Mourning Dove (Zenaida macroura).
What is interesting about the dove's call (and others in the Columbidae family)
is that it is an octave or two lower than calls made by birds of similar
size. The generation of the low frequency call involves an inflated air
sac. The standard piston model states that each halving of frequency
requires a +12 dB increase in excursion. So in comparison to other birds,
this is a significant increase in energy. The spectrogram display has
what looks to be a spin up and spin down for each note. Nothing is
actually spinning here but think of the dove's low frequency call as a large
air mass in motion that doesn't start or stop instantly. It takes time
and effort to move a larger mass which would explain the leading and trailing
tone sweeps.
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