The Logic Off Topic list

> > I know most people cant hear above say 17kHz or so, and thus the
argument
> > for 96kHz sampling rate seems ridiculous.

j.offerman@...>;  wrote
> You are mixing up two *very* different things: 17kHz refers to the
> highest frequency people can hear, whilst the 96kHz refers to the
> frequency at which the sound is sampled by digital recorder.
>
> I.e. a 96kHz digital recorder samples the frequency of the sound that
> is being recorded 96.000 times per second. This has *nothing* to do
> with the actual frequency range of the sound being recorded.

sorry Jim, I should have been more specific, I was commenting on the fact
that 44.1kHz recordings can only reproduce tones up to 22.05kHz, then I was
making the comparison that humans can only actually hear up to 20 odd k
theoretically (and I made a guesstimate of 17k practically - due to  rock
concerts, traffic, computer whine etc...). Then the fact that the higher
tones cant be heard anyway makes sense, however...

I made a half-assed guess at beat frequencies generated by high order
harmonics interacting but Lennart pointed out quite rightly that such tones
are produced from perception through a non-linear medium rather than
superposition in a linear medium (ie. air). Thus to properly reproduce these
beat frequencies you DO need to record as high as you can go.

The only problem then is how to reproduce these tones. Most titanium
tweeters I have seen spec sheets for only reproduce up to maybe 30 or
40kHz - how do the higher frequencies get reproduced?

--
Mark Lennox
Technical Consultant
ENDUSER
Suite 40
Guinness Enterprise Centre
Taylors Lane
Dublin 8
Ireland
Tel: +353 1 4100 665
Fax: +353 1 4100 985
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--

--- In logic-ot@y..., "Mark Lennox" <mark@e...> wrote:
> 
> > > I know most people cant hear above say 17kHz or so, and thus the
> argument
> > > for 96kHz sampling rate seems ridiculous.
> 
> j.offerman@i...>;  wrote
> > You are mixing up two *very* different things: 17kHz refers to the
> > highest frequency people can hear, whilst the 96kHz refers to the
> > frequency at which the sound is sampled by digital recorder.
> >
> > I.e. a 96kHz digital recorder samples the frequency of the sound 
that
> > is being recorded 96.000 times per second. This has *nothing* to 
do
> > with the actual frequency range of the sound being recorded.
> 
> sorry Jim, I should have been more specific, I was commenting on 
the fact
> that 44.1kHz recordings can only reproduce tones up to 22.05kHz, 
then I was
> making the comparison that humans can only actually hear up to 20 
odd k
> theoretically (and I made a guesstimate of 17k practically - due 
to  rock
> concerts, traffic, computer whine etc...). Then the fact that the 
higher
> tones cant be heard anyway makes sense, however...
> 
> I made a half-assed guess at beat frequencies generated by high 
order
> harmonics interacting but Lennart pointed out quite rightly that 
such tones
> are produced from perception through a non-linear medium rather than
> superposition in a linear medium (ie. air). Thus to properly 
reproduce these
> beat frequencies you DO need to record as high as you can go.
> 
> The only problem then is how to reproduce these tones. Most titanium
> tweeters I have seen spec sheets for only reproduce up to maybe 30 
or
> 40kHz - how do the higher frequencies get reproduced?

There is a difference between 'reaching' 40kHz and 'reproducing 
correctly' at 40kHz. My Dynaudio tweeters go up to 45kHz +/- 3dB,
 :-). It's not so much those beat frequencies, but more about impulse 
response distortion. Remember that 40kHz is only 1 octave above 20kHz 
and only 2 octaves above 10kHz. The second harmonic of a frequency is 
essential for the human ear; the brain and human 'hearing' experience 
even harmonic distortion as pleasant. Odd harmonic distortion the 
human ear does not like, :-). So the higher the frequency the better.
That's why certain amps have such a high bandwidth. You should know 
that, :-), as a music consultant. And everything in the signal chain 
should be distorted as less as possible.
Yoonchi.