On Thu, 13 Aug 1998, Denton Taylor wrote:
> >>Surely the sampling rate is that which the sampler samples (asks for
> information from the player of music), while the hearing frequency is that
> of the sound, i.e. different things.>>
>
> I'm no scientist, but it has something to do with the following (Ken, help!)
>
> The theoretical limit of human hearing in the high frequency range is say
> 20,000-22,000 hz. Therefore under Nyquist theoretically in order to capture
> all information in this upper range, which is in analog wave form, the wave
> must be sampled twice.
Yep, as long as the analog information is under 22KHz. You have to force
the analog signal to this band limit by low pass filtering.
>
> However, Nyquist or no, it has become clear that 44khz is not sufficient to
> capture all the harmonic information of a musical recording, which is way a
Of course, the music contains information above 22KHz. If you do sampling
directly on the analog data, you may have aliasing, which may be quite
disturbing in audio. But, again, if you do lowpass filtering, 44KHz is
enough for a "human".
> suprising amount of music is recorded to 2" analog tape, and why records
Well, actually the analog to digital convertors are not ideal. They are
mostly nonlinear devices which introduce some other forms of distortion.
The recent DPCM 1 bit DAC's are the results of an effort to solve the
nonlinearity problem : The 1 bit DAC is definitely linear. So I believe
this is the reason pro studios use analog tapes.
> sound better than CDs. In the near future it appears the sampling rate
> might be bumped up to 96khz (requiring the purchase of new CD players,
> etc.) Perhaps that will be sufficient to finally capture true musical sound.
I do not think 96KHz sampling rate solves this problem. As a matter of
fact, for 12 bit sound samples, in order to make 1 bit DPCM, you have to
have 12 times oversampling, which means 12 * 44 KHz.
>
> To bring it back to photography, I'm not familiar of any application,
> whether inkjet or commercial printing process, that would require an output
> file of greater than 300dpi.
The dpi of the printer is not the only concern to make a faithful
reproduction. The inkjet system is limited to three color dot reproduction
which is no where near to a kodacolor ease photo printer, for example. The
latter one prints a dot at 300 dpi having the exact color (CMY) of the
pixel value, whereas the inkjet printer prints a dot of only one of the
ink colors.
The only OM content is my name. Sorry.
OMer.
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