On 08/10/2009, at 5:48 AM, Rob Danielson wrote:
>
> Hi Paul--
>
> Although its unusual for wind/vegetative "zizz" to be so stationery
> in pitch and in sound level, I trust your experience/memory of the
> situation more. Now that you are alert to the phenomenon, maybe
> you'll be able to figure out how it happens. It is curious, if it is
> a naturally-produced sound.
>
> As for the wing "whirr" phasing, it sounds like the Doppler effect as
> the birds flies towards and away from the mics. Perhaps occurring at
> higher pitches then we are accustom to. Rob D.
>
Hi Rob,
I find it a bit difficult to pinpoint the cause. The recorder was
modded by Oade Brothers and has an additional 6dB gain above the stock
units. I tend to record with the gain set just above 9, so I guess
this is slightly above full gain on a stock unit. I've seen comments
that the stock HDP2 is reasonably noisy once you get close to maximum
gain, and I feel the Oade mods don't completely eliminate this trait.
As a point of comparison I've posted another recording made a week
earlier in calmer conditions, using the same rig. The recording was
made at Gundabooka NP around dawn and birds were calling fairly close
to the mics. The Grey Shrike Thrush calls actually clipped shortly
after the edit I've posted. I've made no level adjustments or
processing beyond downsampling from 88.2khz to 44.1khz and adding 2
fades. The down-sampled wave file was converted to mp3 using the
LAME 3.98.2 encoder with -V 0 and -m s settings. -V 0 is highest
quality variable bitrate preset, and -m s sets encoding to maintain LR
stereo.
I've appended a 7 second section of predawn quiet recorded at the
original location I had the mics set up. The gain setting on the
recorder was not changed between the two recordings.
The segment posted is a little over 7.5 minutes and is roughly 13Mb.
http://www.urbanbirder.com.au/outback-nsw/early-morning-bennets-gorge-track
regards
Paul
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