[plug]audio cds, was slowdown probs

[alan howard]

On Thu, 23 Aug 2001 10:48, Mike Holland wrote:
> On Wed, 22 Aug 2001, alan howard wrote:
> >  unfortunatly cd audio is just as bad. a 44khz sample rate ( normal cd )
> > will not correctly resolve a 9khz square wave
>
> Alan, nor will the human ear. Are you making recordings for animal
> behaviour research :)
>   IIRC, a fourier analysis of a square wave, shows a 9kHz sine wave (which
> you hear) plus 18kHz, and higher harmonics, which you'd hear little or
> nothing of. Both the CD and MP3 standards are designed with the human ear
> in mind. Just as GSM etc are designed for human voice.
>
>   Is there any special problem converting CD to MP3? e.g. some artifact of
> the sampling rate?

if you can , have a listen to a demo on one of pioneers or sonys high sample 
rate systems. your be amazed at the difference it makes to the treble. also 
if you have a signal generator , try changing from square wave to sine, you 
can hear a difference at 9 khz.
also a square wave is made up of odd order harmonics, ie at 9khz it is 9khz + 
 1/3 27khz  + 1/5 45khz  etc sine waves.
rgds
alan howard