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" <> 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
>
"While a picture is worth a thousand words, a
sound is worth a thousand pictures." R. Murray Schafer via Bernie Krause.
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