Ed, the way my head is wired, when I listen to those frogs up close like that, it is as beautiful a sound as any musical instrument. In fact, I think I'll just see what they are tuned at...
(5 minutes later)

There you go. There are 5 frogs total. A quartette and a solo 1 octave lower. The graph shows the frequency and tuning of the highest 3 notes (frogs), but you can see there are four and the peaks in the 1K region is the fifth frog, which is a deep sounding frog.
Each of the 3 that were tracked are playing B6!!! And the forth frog is right there in the grouping sounding to me like he is also at B6.
Let that sink in for awhile... they just happen to be playing musical notes. Music notes are based on time, time is an increment that comes from the rotation of the earth. To create musical scales requires an understand of astronomy. If this is new to you please read my short paper called "What is Sound?" located here:
https://www.decware.com/newsite/DECWARESOUND.pdfAfter you've read the paper, you realize that beyond the 88 keys on the piano, each with a frequency, there are many times that amount of frequencies that are NOT music. Classic example would be an out-of-tune instrument.
So... how do the frogs just happen to select B6? Of course that is only a snapshot (one note) of basically a 3 chord progression


Pretty cool for a group who never went to school.
Steve