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Re: Hi-Freq. Insect?

Subject: Re: Hi-Freq. Insect?
From: "David Ellsworth" davidells
Date: Fri Jun 8, 2007 8:44 am ((PDT))
At 2007-06-08 01:29, you wrote:

>Hi David,
>
>I think that the confusion is caused by the unusual 32 bit file format
>of Doug's recording. When I first tried to open it, I also got those
>strange waveform patterns. However, my old Cool Edit Pro LE opened the
>file correctly. I just uploaded a 16 bit version of Doug's file:
><http://www.avisoft.com/scratch/insect_hi_freq1_16bit.wav>http://www.aviso=
ft.com/scratch/insect_hi_freq1_16bit.wav
>
>Regards,
>Raimund

What confusion are you referring to? I also
opened the file fine once I tried it with Cool
Edit Pro 2.0, which I had to find and download. I
had an old version (Cool Edit Pro 1.0) on my hard
disk, installed a long time ago, but it refused
to launch, saying "The system has not been
configured correctly to run Cool Edit
Pro.  Please run Setup again." Other audio
programs I had just treated the sound as ugly noise, not as neat waveforms.

My filtered versions are from a properly decoded version of the file.

I should have said this earlier: Nice research
finding that Roesel's bush-cricket sample, as it
is similar to Doug's recording in some ways.
Also, I should have posted a 16-bit version of
the original, like you just did. (I almost did
just that, but then for some reason I changed my mind.)

I do not think Doug's recording is of an insect;
I think it is electrical interference from a
power line. It's just too much of a coincidence
for it to be so close to 120 Hz (60 Hz really,
with that alternating amplitude). Listen to
http://ad2004.hku.nl/naturesound/David_Ellsworth/insect_hi_freq1.filtered.w=
av
and it sounds like something very familiar =97 the
sound you get if you touch your finger to an
audio input that is plugged into amplified
speakers. Look at the waveform of
http://ad2004.hku.nl/naturesound/David_Ellsworth/insect_hi_freq1.filtered2.=
wav
=97 I don't think a cricket could maintain such a perfect pattern.

Still, the discussion is far from closed.

* My hypothesis could be refuted if Doug records
and posts a sample where the sound has a
"hiccup", i.e. a departure from the perfectly
regular rhythm or alternating amplitude.
* Somebody could find a cricket species that
sounds exactly like Doug's recording (i.e. is
20-22 kHz and pulses on the order of 120 Hz)
* I could do an analysis on the statistical
properties of the recording's pulse rate (i.e.
how constant it is), and compare it to both a
power line and to a cricket, possibly lending credence to either hypothesis=
.
* We could find a scientific explanation for how
a power line's pulse could be translated into a
high-frequency sound pulsed at double the rate.





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