Subject: Re: [linux-audio-user] sampling at high frequencies
From: Joern Nettingsmeier (nettings_AT_folkwang-hochschule.de)
Date: Mon Jan 26 2004 - 15:41:34 EET
On Mon, 26 Jan 2004, Steve Harris wrote:
> On Mon, Jan 26, 2004 at 11:54:26 +0100, Joern Nettingsmeier wrote:
> > >This is not quite correct. While humans can not hear continuous tones over
> > >20-odd kHz that is not the whole story, the frequency reproduction also
> > >limits the minimum transient rise time, which is detected by a different
> > >part of the ear (IIRC, IANABiologist and my psychoacoustics textbook is at
> > >work).
> >
> > interesting point. but isn't membrane inertia the limiting factor in
> > transient reproduction anyway?
>
> Which membrane?
sorry for not being clear, i was thinking of the speaker membrane of the
playback system. just guessing, though.
> The basilar membrane is responsible for frequency alaysis
> (AFAIR), but its limited by its geometry. Doesn't it detect resonances in
> the narrowing tube? Transients could be detected before the pressure wave
> reaches the basilar membrane, though I'm just guessing here.
>
> > my naive understanding is that min rise time = nyquist freq. if we
> > cannot perceive frequencies above, say, 20k, all we win by faster
> > sampling is more accurate timing information.
> > but there is a worst-case "timing error" of 1/24000 sec, which does not
> > seem much to me...
>
> Its not the timing error - it wont be quatised to the nearest sample
> AFAIK, but you will get substantial ripple from the reconstruction filters
> fi you try to reproduce transients near nyquist- dunno how that is perceived.
>
> > i'd like to read more, but i haven't been able to google anything up
> > about transient perception and reproduction. any pointers?
>
> There seems to be some relevent stuff here:
> http://arjournals.annualreviews.org/doi/full/10.1146/annurev.neuro.23.1.285
> but its a bit over my head.
drat. it's "pay per view". :(
but i guess i wouldn't understand anything anyway.
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