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Re: Questions for audio gurus

Subject: Re: Questions for audio gurus
From: "Julius Thyssen" <>
Date: Thu, 23 Feb 2006 20:49:48 -0000
Gianni Pavan <> wrote:

> real-time spectrographic display. In this way, while recording or
> when playing back the files,  we can "see", rather than "hear", any
> ultrasonic component.
> From a purely technical point of view it is important to consider
> that real-world anti-aliasing filters are not perfect and any signal
> with frequencies, including those of harmonics, that cross the
> Nyquist frequency may produce artifacts that may corrupt the quality
> and integrity of the signal. Poor a-a filters at 22.05 or 24 kHz may
> produce artifacts that fall down to audible frequencies or, in any
> case, corrupt your spectrographic images. Thus, moving Nyquist up,
> you also lower the possible impact of aliasing.
> Any comment on these thoughts will be appreciated,

Yes, I agree on that. We here in this group are more likely
to not only want to sample the sound as we are able to hear it,
but also to store it for historical and maybe scientific purposes.
The importante of high samplerates all depends on your
(later) plans with the sound you record.

For (human) music I would personally say 48 kHz is fine.
This is just out of personal experience, and taking into account
that the reproducing medium (the headphone or loudspeaker)
wasn't made for supersonic audio, and 48 kHz really
sounds warm enough, and is extremely close to having
a decent In-Out response for the human ear. Even the
anti-aliasing artifacts are out of hearing range.

Personally I'm still quite sad the CD (44.1 kHz) format has
gotten so 'big'. It would have been so much better if only
'they' changed it to 48 kHz as soon as it was possible (in 1986).


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