Dan Dugan <> wrote:
>
> I've only examined the 3032 at 44.1 sampling rate, but it looks like
> it's going strong at 20K. Sound Devices publishes the response of
> their preamps hidden somewhere on their web site, but I can't find it
> today. As I recall they're good to at least 50K.
>
> Next time I have access to a 722 I'll try a night recording at high
> sampling rate with 3032s, and slow it down with SoundHack or
> something. Thanks for the idea.
>
> -Dan Dugan
>
That would be very interesting, but some of the higher intensity bats could be
present in your 44.1 recordings, as their calls include the 16-22 kHz interval.
In a sonogram you would see 4 to10+ millisecond tonal pulses at intervals on
the order of 100-150 ms. These could be nearly constant frequency, but are
more likely to be declining FM sweeps from above the Nyqvist.
As Gianni Pavan pointed out long ago, the antialiasing filters on the Sony
consumer DATs are quite 'soft'. With a microphone which didn't roll off at 20
kHz, some bat calls were often aliased down in 48 kHz tape recordings. The
aliased calls sweep 'the wrong way' for North American temperate zone bats,
so they're usually easy to recognize by eyeball.
I fail to recall if Gianni (or others?) have reported bench testing the
antialiasing filters of the 722, but you might have material for a biological
assessment at 44.1.
Bill R.
________________________________________________________________________
________________________________________________________________________
"Microphones are not ears,
Loudspeakers are not birds,
A listening room is not nature."
Klas Strandberg
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