From: Rick.Moen@f207.n914.z8.rbbs-net.ORG (Rick Moen)
Newsgroups: sci.skeptic
Subject: Re: Sampling and human hea
Date: 13 Sep 92 06:32:17 GMT

Reply-To: Rick_Moen@blyth.com

In article <LT0yqB3w165w@tsoft.sf-bay.org>, bbs.ruscal@tsoft.sf-bay.org
(Russel Mar) wrote as follows:

> dmoran@world.std.com (david r moran) writes:
>
>> In article <1992Sep11.173910.279@u.washington.edu>
> mpark@milton.u.washington.
>> >In article <2250287@overmind.citadel>
> only_bbs!JOHN_LOCKARD@overmind.mind.or
>> >...
>> >> Between the sampling rates of twice the freqency and four times
>> >> the freqency of the sine-wave you get complex phase, frequency,
>> >> and amplitude distortions that aren't easy to filter out.
>> >>
>> >> That's why to get the 35KHz wave that the human ear is supposed
>> >> to detect you need at least 100KHz or more to reproduce the
>> sound. >
>> >Does anyone have a reference to the [British?] research that
>> >supposedly demonstrates that the ear can detect "nuances" in
>> >sound up to 35kHz?  Or any research that demonstrates that the
>> >conventionally-accepted human hearing range (~20Hz to ~20kHz)
>> >needs to be reconsidered?
>> >How about the idea that signals must be sampled at _three_ times
>> >their highest frequency?
>> >
>> >[newsgroups: comp.sys.atari.st - where this started
>> >             rec.audio - surely some audiophile knows a reference
>> >             sci.skeptic - to keep the audiophiles honest :^)
>> >  can't decide where to followup-to...]
>>
>> This is all bullshit. What such people need (among other things) is
>> to get an audiogram. First things first: what one can and cannot
>> hear. Test self before posting. Or writing in a magazine.
>
> =======================
> Having used a Hybrid Arts (R.I.P.) ADAP sampler, I can tell you that
> the accepted minimum requirement is to sample at 2x the max. freq. you
> want to reproduce/record.  If you are baffled, look up the Nyquist
> Theorem; CD's sample at 44.1k and DAT at 48kHz for this reason also.

Oh, goodie!  A refugee thread from rec.audio.  That's a big improvement
on the rejects from talk.origins and blather.god.pro-or-con we usually
get.  I guess I'll bite.

Yes, what Lockard is quoted as saying sounds like pure double-talk,
and Nyquist's Theorem applies exactly as you state.  The real problems
with commercial-quality A/D conversion are (1) the excessively sharp
filters required to meet the Nyquist criterion while still allowing
adequate high-frequency content (which introduces major phase-distortion
and other problems), (2) inadequate digital sample size (which results
in poor capturing of low-level detail if one is to also leave an
adequate ceiling against overload), and of course (3) the questionable
quality of circuitry in the analogue stages of almost all recording-
industry "digital" electronics.

Unfortunately, the low sampling frequency and digital sample size
applicable to CDs were assigned permanently back in the neolithic days
of A/D converters, and, at that, represented a "dummying down" from the
then-current best (e.g., Soundstream) in order to hasten the monetary
bonanza for even the least capable.  Personally, I'll wait for a CD-2
format with more recent A/D technology, which _should_ finally be
routinely more listenable than a modified $20 AR turntable, $50 used
Grace 707 tonearm, and $100 Grado phono cartridge.  About time, too!

Best Regards,
Rick M.

 * Origin: The Skeptic's Board in San Mateo - Bay Area Skeptics (8:914/207)