From: Dan Dugan <>
>
> Bhaksar, you wrote,
>
>
>>>Greetings from India. I recently joined for the nature
>>>recordist group. I am a wildlife researcher primarily
>>>focussing on large mammals. I am very keen to record
>>>the sound of the birds and the communication of the
>>>mammals especially the infras sound.
>>>
>>>I have written twice to this group to suggest the
>>>basic equipment required for recording the call of the
>>>birds and infra sound mic, recorder and to analyse the
>>>data later, or any other related accessory that I have
>>>to take.
>
>
> For recording natural environments, I get great results Sharp MD
> recorder and a pair of high-sensitivity omnidirectional mikes mounted
> on my shoulders. See http://www.minidisco.com for prices. I built my
> own wire cage windscreens with fake fur coverings.
>
> If you want to record specific species for analysis, I've heard good
> things about the Telinga "Stereo DAT" model parabolic mike, see
> http://www.naturesongs.com/Telinga.html for a U.S. source,
> http://www.telinga.com for the maker in Sweden.
>
> Others will tell you about infrasound recording; I think it might be
> possible to modify the larger digital recorders (like the HHB
> PortaDAT) to extend the low-frequency response of the mike inputs.
I don't have the specs for the discontinued PortaDAT, but the specs of
the HHb Portadisc give it a low end frequency of 10Hz. If I remember
right, elephants don't go that low, so if that's the infrasound that's
wanted, they could be recorded with a unmodified Portadisc. Probably
many other recorders as well, though you'd have to verify that. Decide
on the level of infrasound you need first.
I second the MKH-110 as being a very good mic for infrasound and a very
good mic in general. It holds it's own very well against a MKH-20. A
great majority of the elephant infrasound work has used MKH-110's.
There is one concern that is generally not too well thought about in
recording infrasound. That is that the suspension of the mic may be
resonating in this range. There is some discussion about this in the
link below, though I think the author is being overly pessimistic, and
he's really talking about studio type recording more than nature recording:
http://www.microphone-data.com/pdfs/Wind and vibration.pdf
I've not seen this resonance problem with the SASS/MKH-110 setup I use.
But I need to do more testing to be sure it's not in there somewhat.
That setup is certainly very good at recording the low frequency end.
So, to record elephants in the field, if I was close enough, all I'd
take is the Portadisc in it's Portabrace field case with it's extra
batteries, disks and field note cards, and the SASS/MKH-110 with a spare
9v battery and it's wind cover. And some 5-pin XLR cable to hook the two
together. Keep the field kit simple. Of course that does not include
whatever it would take to be safe close to wild elephants. I don't have
to deal with that here so have no experience recording them.
As far as analysis, if this is for publication in somewhere like a
bioacoustics journal, you need to study what they will accept in the way
of equipment. You may have to get into highly calibrated equipment for
this, being able to record perfectly is not going to be their criteria.
They have certain pieces of gear they think are all that records
perfectly, ignore all else, in spite of the fact that some of that gear
is not all that wonderful for getting good listening recordings. And
that gear is generally very expensive.
Analysis covers a lot of ground, you need to define what analysis you
intend to do and it's purpose. Many pieces of software can do sonograms,
for instance, though the quality of those does vary quite a bit. And
sonograms in infrasound will be harder to find as most sonogram software
scales only down to 20Hz, and it's math is giving a really blurry and
undefined picture in even that level.
Walt
________________________________________________________________________
________________________________________________________________________
|