Very nice, John. It indeed seems that I spoke too soon when I said clipping=
probably had nothing to do with it. Inspired by your experiment I did the =
same but then purely digitally. Turns out that if you add a high amplitude =
tone to a white noise background, the noise is attenuated somewhat when the=
digital signal is clipped. Makes sense perhaps, because the clipped peaks =
contain background noise that is simply removed as all clipped values are e=
ffectively set to a fixed value. Clipping should be pretty strong though, s=
o I don't know if it can account for Laura's phenomenon. Best, Gabriel
--- In "John Crockett" <> wrote:
>
> Hi Laura,
>
> Do all of your artifacts correspond to clipped signals? I just tried a li=
ttle experiment with an ME66 and both the PMD-670 CF and MZRH1 MD recorders=
. I turned on a fan to create some good background noise, and then whistled=
loudly. First I had the record gain low enough so the whistle signal did n=
ot clip. Then I turned up the gain so it did clip. In the resulting sonogra=
m, a white (low volume) "shadow" appears in the frequencies below the whist=
le signal wherever it is clipped, eclipsing the fan noise, just as it appea=
rs in your sonogram. The worse the clipping, the more pronounced the "shado=
w."
>
> In the unclipped samples, the fan noise continues uneclipsed.
>
> Is there something about clipping that overloads the preamp so it cuts ou=
t other frequencies besides the signal that is causing the clipping?
>
> John Crockett
>
> --- In "laura.hilberg" <laura.hilberg@>=
wrote:
> >
> > I was using a PMD 680 recorder and a Telinga microphone with a parabola=
. I was using manual gain (no automatic), but I had some difficulty getting=
close enough to the birds for a clear signal and then having them shift po=
sitions so they were facing me more and being blasted away. And this is my =
first time really recording, so inexperience definitely plays a role (and t=
hankfully, they get better as they go along).
> >
> > Can you say what you mean by the gain needing to be set at a fixed leve=
l so that the sound doesn't clip? It was fixed, so I don't think that would=
be an issue.
> >
> > And sorry about the sound sample - it wouldn't let me post it (464kb) b=
ecause it said there wasn't room.
> >
> > Thank you so much!
> >
>
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