a softer sound, that almost sounds like a second
Anna's Hummingbird doing a dive sound in the distance. Is that what it is?
When I do a band-pass filter at 4400 Hz, what is
left is just the main dive sound... a very strong
tone, slightly falling in pitch, with amplitude modulation (tremolo).
When I resample the recording to 6800 Hz to get
rid of the main component of the dive sound, what
is left is something that sounds like a "bump" or
"clank", even like a button being pressed. I
think this is the phenomenon you're talking
about. Doing band-passes on the various parts of
the spectrogram it seems to occupy result in a
totally different sounds, that =97 on their own =97
plausibly sound like something a hummingbird
could do; but the character of these band-pass
results seem totally unrelated to the unfiltered
(but resampled-to-6800-Hz) sound. It seems to me
that it is a broadband sound that resonates
slightly at some frequency bands, with the
resonances disproportionately standing out in the
spectrogram (disproportionately, relative to
their true importance). I think these resonances
are what you're talking about when you refer to
"distinct frequency bands"; please correct me if I'm wrong.
Do you have any more recordings that show
something like this, and if so, could you please
share them? It would be quite valuable in analyzing what this is.
At 2008-01-26 10:31, Doug Von Gausig wrote:
>I know this is an old topic, but, to my knowledge it has never been
>conclusively settled.
>
>Having read Louis Baptista's work
>(<http://tinyurl.com/ysl4l8>http://tinyurl.com/ysl4l8) and many,
>many others over the years, I am still unconvinced myself how this sound i=
s
>made. Most of the recordings I have of the sound have a distinct wing tril=
l
>preceding them. That trill is the sound of wings building up speed before
>the pullout at the bottom of the dive. But I also have several samples tha=
t
>lack that precursor and which were recorded without seeing the bird. That
>in itself means little, but the interesting thing is that both types of
>samples often show two distinct frequency bands at the same instant. (see
><http://tinyurl.com/2xy3ve>http://tinyurl.com/2xy3ve) - hear the sample at
><http://tinyurl.com/2xy3ve.This>http://tinyurl.com/2xy3ve.This
>is something we commonly see in oscine
>Passerines, since they have two syrinxes, but not in non-oscines. The two
>bands may indicate more complex vocalizations that we expect in hummers,
>but it may also indicate that there are two different places generating th=
e
>sound (like two different tail feathers or groups of feathers). It seems
>unlikely to me that these two bands come from vocalizations...but maybe...
>
>I'd be interested in hearing your thoughts and experiences with this.
>
>Has anyone ever seen an Anna's Hummingbird make this sound while sitting
>stationary?
>
>Does anyone know of any high-speed movies of the dive and sound being made=
?
>
>Other thoughts about how we could conclusively settle this? Or do most
>believe that Baptista's work settles it?
>
>Doug
|