Just to end the conversation on humorous note - I once composed a symphony =
for bats - it was almost enirely inaudable to human ears - bats were my int=
ended audience. Amazing the kind of nonsense you get up to at art school eh=
?
Anyway some of this conversation is beyond my ken now - though I find it fa=
cinating - all I really want to know is - would a Tascam 680 with low noise=
mics be ok ?
--- In "Raimund" <> wrot=
e:
>
> >I don't want to prolong this discussion any further but I will just
> >add that digitisation is a very non-linear process and that sampling
> >will generate lower "beat" tones which come out as enharmonic noise >or =
quantisation noise. A reasonable mic won't do this.
>
> >However, I am a pragmatist and it's the results that count, not the
> >theory. Complex sounds like a bird calls, bat social calls or mammal
> >squeaks which are far from a sine wave will sound "gravelly" when
> >played back at slower speeds.
>
>
> David,
>
> The effects that you describe might be the quantization noise of poor 8 b=
it time expansion bat detectors. You mentioned that you also used PCMCIA da=
ta acquisition boards for recording ultrasonic bat sounds. These devices ho=
wever do not have integrated anti-aliasing filters, which can lead to stron=
g aliasing effects.
>
> But if you used a high-quality recording system with proper preamplifiers=
and anti-aliasing filters, the digital sampling will not introduce any art=
ifacts. In fact, it is far better than the ancient analog tape recording te=
chnology.
>
> Listen to my own bat call recordings at http://www.avisoft.com/sounds.htm=
#bats and http://www.batcalls.com
>
> Some of these recordings were also made by using conventional 8 bit time-=
expansion bat detectors with poor preamplifiers and noisy microphones, whic=
h is indeed audible. But there are also better recordings that were made wi=
th high-quality 16 bit recording systems.
>
> Best regards,
> Raimund
>
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