Doug,
I measure 120.02 pulses/sec! There's a pattern which never deviates,
in which every "even" pulse has a low amplitude and ever "odd" pulse
has a high amplitude ("even" and "odd" are arbitrary of course). This
means the actual period of the sound is 60.01 Hz, which really
strongly suggests to me that this is an electrical disturbance from a
power line. I'm going to write a program to measure the
moment-to-moment deviation in the pulse rate; perhaps this can shed
more light on whether it is too regular to come from a living creature.
Have you found any pattern to the circumstances under which this
pulse shows up in your recordings? It would be nice if you could
record this at a higher sample rate. At 44.1 kHz, its spectrogram is
cut off sharply, so we're not hearing the complete sound when it's slowed d=
own.
BTW, I had to struggle to find a program that could open
insect_hi_freq1.wav... turns out it is 32-bit floating point.
At 2007-06-07 11:49, Doug Von Gausig wrote:
>Every once in a while I notice these very HF insects in recordings -
>they're often at 20,000 Hz and higher. When I resample them down to my
>range and increase the volume, they sound like regular tree crickets.
>They're often diurnal.
>
>I've posted an example at
><http://www.naturesongs.com/recordists/insect_hi_freq1.wav>http://www.natu=
resongs.com/recordists/insect_hi_freq1.wav
>( or
><http://tinyurl.com/nd3y6>http://tinyurl.com/nd3y6). In this
>example, recorded in central Arizona
>today at 11 am (86 deg.F), the first 3 sec. are "raw" - you can see the
>sound up around 21,000 Hz, the next 3 sec are resampled 4X, and the final =
3
>sec are the resampled portion boosted 20dB, so I can hear it.
>
>The individual pulse rate is about 120 pulses/sec, so he's really humming!
>
>What are these guys?
>
>Doug
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