you posted but there's enough going on that it isn't horrible or anything l=
ike that. My guess is you can get significantly closer to what you want wit=
hout investing in lots more expensive equipment.
2) There's periodic signals from 5.6 kHz increasing to 6.0 kHz. Do you know=
what they are, are they important?
3) Others will know much more but my first reaction is that your mics aren'=
t suffering from the humidity --- it basically sounds oaky and the question=
is just how to emphasize what you want.
4) Are their possibly high Hz sounds that are lost? Some North American bat=
s make "social" sounds in the 10-18 kHz range (not ultrasonic echolocation =
sounds) that might not turn up on a recording with regular mic but not need=
ultrasonic techniques and equipment to be audible.
5) Fixed size confined spaces can result in "standing waves" that over emph=
asize some frequencies. I didn't hear that in your recording, but my ears a=
ren't great --- ask others. Could the confined space be a factor?
Anybody who get wet & dirty making a recording gets lots of credit! Let us =
know how it goes.
Cheers!
Steve P
--- In Richard Folwell <> wrot=
e:
>
> http://soundcloud.com/user2340027/tmn-bat-wings-ear-cave-april-2010
>
> I'm sharing this not because I think it is good, but because I think it
> was an interesting idea that fails for a number of reasons, which
> probably are worth sharing.
>
> The recording is of the flight of bats in the Ear Cave, Taman Negara,
> Malaysia. Conditions inside the cave were hot and humid (unfortunately I
> do not have numbers, but I had a fairly dry shirt when I went in, and a
> completely sodden one when I came out less than an hour later).
>
> Obviously the sound of bats wings is not loud (though when they flew
> close they could produce "wind noise" from the microphone, even though I
> was using a windshield!). The microphone (AT 8022) does not have a
> published floor noise level in the AT data sheet, so I can only assume
> it is something they are not particularly proud of. To get the
> recording to normal listening levels I used the following method (with
> Audacity):
>
> - identify any obvious sound peaks, zoom in a lot and reduce the volume
> of the peak (generally by -3 or -6 dB)
> - normalize
> - repeat until the floor noise started to become objectionable when
> listened to with headphones
>
> I am assuming that the white noise audible in the background is due to
> microphone self-noise. In the cave there was no running water, and the
> nearest running water outside is some distance away.
>
> - is this noise typical of microphone self-noise?
>
> Water dropping from the cave roof is audible throughout. However some
> of the sounds both sound and look different from those that are clearly
> water drops. For example in the section 3m 42.023 s to 3m 50.395 there
> are three short duration louder sounds. The first is clearly a water
> drop, the second two sound much harsher, and have a very sharp attack.
>
> - could these sounds be humidity-induced microphone noise, or are they
> just different sounding water-drops?
>
> On the problem of recordist noise, for this kind of recording I would
> consider in the future using a long cable run between the microphone and
> recorder, though even in this small cave several tens of metres of cable
> would be needed. (Otherwise learn how to keep completely still, and
> learn sign-language :-)).
>
> For improving the microphone, I am considering a pair of Rode NT1As, set
> up in some sort of boundary array. Obviously a different recorder would
> be needed (and/or a pre-amp providing the phantom power). One thing I
> learned from this trip is that being able to carry all the kit in a
> small bag is really useful, as is having a reasonably short set-up time.
> The AT8022 in the Rycote windshield + tripod went into a sports bag OK,
> and could go through the narrow access to the cave (would use a better
> small rucksack in the future).
>
> I would appreciate any suggestions for better microphone + recorder
> combinations that would meet the portability requirement (ideally with
> schematics if any DIY is involved :-)).
>
> Thanks,
> Richard
>
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