Subject: Re: [linux-audio-user] sampling at high frequencies
From: Joern Nettingsmeier (nettings_AT_folkwang-hochschule.de)
Date: Mon Jan 26 2004 - 12:54:26 EET
Steve Harris wrote:
> On Mon, Jan 26, 2004 at 10:19:59 +0100, Joern Nettingsmeier wrote:
>
>>imnsho, all this sampling rate hype is a clever industry ploy to keep
>>people from thinking that their hardware is finally good enough and they
>>can stop buying now.
>
>
> Probably true but...
>
>
>>people can't hear over 20k. period. 48k sampling rate gives you 24k
>>minus what's cropped off by the aliasing filter. granted, higher
>>sampling allows you to use a simpler, less steep aliasing filter, and
>>some people claim to perceive an improvement from that. but even then,
>>96k should be enough.
>
>
> 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?
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...
i'd like to read more, but i haven't been able to google anything up
about transient perception and reproduction. any pointers?
for the record, here's a 1998 aes paper that elaborates on the
consequences of higher sampling on filter artifaces in the audible
range: http://www.nanophon.com/audio/antialia.pdf
-- "I never use EQ, never, never, never. I previously used to use mic positioning but I've even given up on that too." - Jezar on http://www.audiomelody.comJörn Nettingsmeier Kurfürstenstr 49, 45138 Essen, Germany http://spunk.dnsalias.org (my server) http://www.linuxaudiodev.org (Linux Audio Developers)
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