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8. Re: High frequency recording

Subject: 8. Re: High frequency recording
From: "gus" leudar
Date: Tue Nov 9, 2010 8:35 am ((PST))
Thanks again Raimund - it is my understanding that interactions between ina=
udible high frequencies may cause "beating" or new tones at lower frequenci=
es which are audible - however I also assume the microphone would just reco=
rd these reultant audible frequencies regardless of whether or not the inau=
dible frequencies were removed.
However it may have some effect.

--- In  "Raimund" <> wrot=
e:
>
> > Thaks again Raimund - I have an annoying habit of asking questions unti=
l I
> > really understand something -
> > are you saying that there is no advantage to having 4 samples represent=
ing a
> > waveform rather than say 2 samples ? Does this mean 2 samples is suffic=
ient to accurately record a waveform ?
>
> Hmmm, that would depend on the bandwidth of the waveform and the frequenc=
y range that you are interested in.
>
> If you sampled for instance a pure 20 kHz sine signal (which does not hav=
e any harmonics) at a sample rate of 44.1 kHz, then the signal is in any ca=
se accurately represented.
>
> If the waveform however had an additional harmonic component at 40 kHz, t=
hen it was not sufficient to accurately represent that waveform by using a =
sample rate of only 44.1 kHz. The inbuilt anti-aliasing filter of the recor=
der would then just remove the harmonic at 40 kHz, which would of course ch=
ange the original waveform. Instead one had to use a sample rate of 96 kHz =
for instance. Nevertheless, if you were not interested in the harmonic comp=
onent at 40 kHz (which is in any case inaudible for the human ear), then it=
 would also be acceptable to record it at a rate of 44.k kHz only.
>
> Regards,
> Raimund
>
>
> this is what I meant. If you sampled the waveform
>








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