"Steve Swift" wrote in message
...
I know this is probably holy war territory, but I'm hoping for some
interesting ideas.

Starting with an audio CD I can take a "bitwise" image, using something
like Nero. I can then write that image to a writeable CD. I can take a
bitwise image from the writeable CD and compare it to the bitwise image
taken from the original CD. They are identical (with the possible
exception of a time stamp inserted in the image).

My brother-in-law claims to be able to hear the difference between the
original and the copy, but only when the copy was written at greater than
4x speed.

What plausible causes exist for the audio being different when the
individual bits being read off the CD are not? They may arrive with subtly
differing timings, but the sequence is identical. I'm sure the timing of
the bits varies every time a CD is played, due to varying rotational
speeds of the CD.

--
Steve Swift
http://www.swiftys.org.uk/swifty.html
http://www.ringers.org.uk

If you can do a double-blind test, and he can do this reliably, then you
have something. The only mechanism I can think of that could *possibly*
account for sonic differences is if the copy is so poorly burnt that the CD
player has a hard time reading the disc and there's a lot of interpolation
going on. It would then be useful to repeat the DBT using another CD player
of competely different type to see if the same results are obtained.
Otherwise, two bit-identical CDs will necessarily sound the same.

S.

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http://audiopages.googlepages.com