Gabriel,
That makes sense, though I'm not sure why people would use a measure that you
get from a chart type other than the ones that they provide! Unfortunately,
while Raven Pro apparently generates power spectra, Raven Lite does not (and
the price difference is all-important for my students!).
Raven Lite's the only sound analysis software with which I'm familiar; this is
probably unreasonable, but do you happen to know of any very inexpensive
software that can generate power spectrum charts?
Thanks,
Alan
--- In "mipartitus" <> wrote:
>
> Hi Alan,
>
> "Peak frequency" is not a well-defined term, but often this measure is taken
> from a power spectrum, not a spectrogram. A spectrogram (which you use, and
> which indeed is more useful for visual identification) is a power density
> plot as a function of time and frequency. A power spectrum is a power density
> plot as a function of frequency only. It might well be that in your second
> example, Arethaea phalangium, the maximum power ("peak frequency") is around
> 15 kHz. It is hard to tell. I don't use Raven myself, but I am sure it can
> make power spectra. Look for a plot with frequency on the x-axis and power
> ("dB") on the y-axis, and determine which frequency the maximum value is at.
>
> Best, Gabriel
>
>
> --- In "symmerista" <aharvey@> wrote:
> >
> > Greetings,
> >
> > My Field Biology class and I have been recording unknown birds and insects,
> > as well as developing libraries of known local species and "sound keys" to
> > help them identify their unknowns. We use Raven Lite to visualize the sound
> > files. For crickets and katydids, we often see "peak frequencies" in the
> > species descriptions. We were hoping to be able to use peak frequencies in
> > our keys, but now I'm not so sure that will work.
> >
> > For some species, the published peak frequency clearly matches up with the
> > spectrogram of the corresponding call (e.g., 3.4 kHz in Neoxabea bipunctata
> > on this page: www.bio.georgiasouthern.edu/bio-home/harvey/peakfreq.html -
> > I don't yet know how to post images more directly to the group!).
> >
> > In other case, I do not see how the peak frequency was determined. E.g., in
> > the second species, Arethaea phalangium, the peak is listed at 15kHz, but I
> > don't see how you would conclude this from the spectrogram.
> >
> > Can anyone provide some insights here?
> >
> > Thanks!
> >
> > Alan
> >
>
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