Warning: this comes from pure speculation. But if a recorder is to have
a flat frequency response down to 20Hz, the DC blocking caps would have
to be sized large enough to have a corner frequency below that, and they
do not act like a brick-wall filter--cutting off everything below that.
So I would guess that most recorders would be able to record a 5Hz
signal. The question would be how much it is attenuated. If you have the
ability to test for that, you could compensate in post processing. If
you have a mic preamp that would pass infrasound, you'd be better off
using the line input on the recorder. I would also guess that you'd want
to record to an uncompressed file format because there might be
something in the MP3 encoding that ignores infrasound.
If anyone has any real experience with this, I'd be interested.
Regards, Robb
Randy Perretta wrote:
>
> I'd be real careful. Very few recorders go that low. Most bottom out
> at 20Hz. They usually have DC blockingcaps on the inputs. Bass
> response is quite commonly associated in quality with something that
> came from the wrong end of the elephant.
>
> I just Googled for digital recorder frequency response. After a few
> pages, I gave up. 20Hz is it.
>
> Maybe someone knows of something portable that goes to DC. Personally,
> and this is just me, Id be looking at scientific Or seismic gear
> (there's plenty of infrasonic seismic gear out there suitable for
> field work) rather than audio or contact the research staff at a place
> that does whale research and see what they use.
>
> Good luck,
>
> Randy
> www.calmediaarts.com
>
>
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